CHASING THE HIGH ORP

Adventures with Ionized Water

by Walter Last

Ionized water has several health promoting qualities. I have no doubt that the most important of these is the strong antioxidant or reducing property of alkaline ionized water. This led me to experiment with my Jupiter Masterpiece (equivalent to the Technos Ionizer in North America) to establish the conditions for consistently generating the highest antioxidant potential in my water.

Here I want to share some of my experiences in the hope of helping others to improve the quality of their ionized water. I must confess that the task turned out to be much more difficult and frustrating than expected but I am very pleased with the final outcome.

Lets start with some basics. In chemistry oxidation and reduction are now commonly defined as gaining or losing electrons. Oxidation is the loss of an electron from a substance, while in reduction an electron is gained. Oxidation and reduction occur simultaneously in two substances. Oxygen is the most familiar electron acceptor or oxidiser. Iron rusts by combining with oxygen. Thereby the iron donates electrons and is oxidised while the oxygen gains electrons and is reduced.

The antioxidant activity can be measured as the Oxidation�Reduction Potential or O.R.P. For this I used an ORP meter (Milwaukee SM 500), which indicates the presence of free or loosely bound electrons as a negative ORP up to �1000 mV. An ORP of 0 is neutral while an oxidising potential can be measured up to +1000 mV. The ORP scale officially extends from +1200 mV to � 1200 mV. However, with this method we cannot measure purely organic antioxidants, such as vitamin E as their electrons are much too tightly bound, although vitamin C is partly ionised and can be measured to some degree.

To confuse things, a high negative ORP can also result from a high level of dissolved hydrogen, and in this case it does not have any antioxidant property. Large amounts of hydrogen are produced at slow flow rates when the water becomes strongly alkaline with a pH over 10.0.

The principle of antioxidant activity is the availability of electrons to neutralise any so-called free radicals with oxidising qualities that may damage biological systems. The electrons present in alkaline ionised water are highly reactive and react much faster than organic antioxidants to neutralise free radicals.

Furthermore, as we age our body structures lose elasticity; everything becomes more rigid. On a biochemical level this increasing rigidity is due to cross-linking of structural bio-chemicals, which in turn is due to a loss of electrons. Providing the body with an abundance of highly reactive electrons can be expected to slow cross-linking reactions and, with this, the aging process.

Finally, all biochemical energy in our body is produced by transferring electrons from food molecules onto inhaled oxygen. Having more available electrons may help us to produce more energy. This may be the reason why some individuals feel more energetic on ionised water.

From this outline you can see why I am so interested in a high negative ORP. The higher the ORP, the stronger the healing qualities. However, this does not mean that it is advisable for beginners to start with a high ORP. As with exposure to sunlight it is best to start with low doses and increase gradually, and even that may from time to time produce some healing reactions as with temporary inflammations, mucus discharge and skin rashes.

Additional healing factors for most individuals are the alkalinity of the water and its low surface tension. Most of us are overacid and benefit from our lymph fluid becoming more neutral. However, this is only a minor factor in using ionised water as we can alkalise more quickly and cheaply by taking sodium bicarbonate. The lower surface tension, on the other hand, improves the absorption and use of nutrients.

My Observations

In my initial experiments it appeared that the slower the flow rate the higher the negative ORP. Therefore I tried to let the water run at the slowest possible rate, about 7 minutes per litre and at the highest ionising setting of 5. This usually gave an ORP of up to �350 mV and a pH of about 10.7. A flow rate of 5 minutes per litre tended to give somewhat lower ORPs and a pH of about 10.0 to 10.5. However, a slow flow rate combined with a high pH eventually caused problems with calcium precipitation. My bore water out of the tap has an ORP of about +250 and a pH of 7.1.

Then I obtained a TDS meter, which measures total dissolved solids or ionic minerals in parts per million or ppm. I found that my bore water has about 350 ppm. After some good rain it would drop towards 300 ppm and also the ORPs were usually lower, say about -250 mV and sometimes much less, even without any rain.

A friend used town water supplied from river water, which in turn was rainwater with a low TDS of about 150 ppm. Initially his ORP readings were only �60 to �120 mV. The highest ORP was with a very slow flow rate that produced a pH of 11.7. I suggested using a calcium insert to increase the mineral content of the water and that increased the ORP to about �200 at a higher flow rate and lower pH.

After ionising the TDS value of the reduced water may be higher or lower than the original water. At lower pH values up to about 9 or 9.5 the TDS tends to increase, either because minerals are now more concentrated or just more strongly interacting with the electrodes of the TDS meter. However, with higher pH values the TDS becomes increasingly lower and continues to drop over time as large amounts of calcium precipitate.�

Coming back to my experiments, I was surprised to notice that higher flow rates could often generate higher ORPs with lower pH. With a flow rate of between 1 and 4 minutes per litre I could sometimes obtain ORPs of over -600 mV at a pH of 8.5 to 9.5. Once I even had an OPR of over -600 with a fast flow rate and a pH of 7.9. However, after some time the ORPs dropped back to about �300 mV. (I know now that this was due to calcification of the alkaline electrodes).�

Sometimes I had the highest ORP at a flow rate of nearly 1 minute per litre and sometimes at 4 minutes per litre but usually somewhere in-between and close to 3 minutes per litre. However, this may be different with different ionisers and different water. Ionisers with more or stronger electrodes obviously will have higher optimal flow rates, while water with lower mineral content will probably need lower flow rates.

The following table shows �typical� differences in ORPs at different flow rates in seconds per litre. These were measured simultaneously with three different probes to show their varying sensitivities. The first line for each flow rate shows the results about 30 to 60 minutes after ionising and the second line in the same samples the next day.

Table 1

ORPs at different flow rates

Most values are higher the next day. To see how long properly stored water keeps its charge I kept a sample for 10 days. I thought by waiting for 10 days I could more easily calculate the daily rate of decline. To my surprise it measured over �700 mV.

This inspired me to measure ORP values on consecutive days in the same batch of ionised water, which I stored separately in several small bottles. The results are in the following table:

Table 2

Setting 5, flow rate 3 minutes per litre

This means that to obtain reliable measurements one should repeat the measurements for several days. Depending on the sensitivity of the electrodes the highest value may be reached somewhere between 3 and 7days. Most surprising to me was the close agreement of all 3 probes on the seventh day. Sometimes a reading can be high to start with but then it is not very stable and may for several days show strong fluctuations. (However, see also below my more recent results with the Modified Vinegar Cleanse).

I assume that the reason for this unexpected behaviour of the probes is the presence of oxygen and other oxidising species in the reduced water. These gradually become extinct by reacting with the reducing chemicals. Electrodes can then give a truer picture of the number of reactive electrons in the water. While the amount of oxidising ions can be expected to be very small as compared to the reducing ions, they have a strong influence on the probes because of the exponential nature of the electrode sensitivity.

To illustrate tis point, a certain number of reducing or oxidising ions may give an ORP reading of + or �100. A ten times greater amount may read + or �200 and a hundred times greater number + or � 300. In this example only 1% of oxidising ions will reduce the ORP reading from �300 to �200. After several days almost all of the oxidising species will have been eliminated and the ORP measurement is now close to �300.

However, in reality the exponential effect is even greater. Vinny Pinto on his Negative Hydrogen site (www.negative-hydrogen-ion.org) has calculated that every increase in negative ORP by 59 mV means a tenfold increase in the number of reactive electrons, while a 118 mV change in the ORP relates to a hundredfold change in electrons. Extending these calculations somewhat further we obtain a ten thousandfold and a millionfold change in electron density when the ORP changes by 236 mV or 354 mV.

To see how the ORP changes in less strongly reduced water during storage I made two additional tests. I produced one sample with a flow rate of 2 litres per minute on the highest ionising setting of 5 and another one at the same flow rate at the lowest ionising setting of 1. The results were as follows:

Table 3

Setting 5, flow rate 2 litres/minute

Table 4

Setting 1, flow rate 2 litres/minute

If you compare table 3 with table 2 you will notice that the first measurements from 30 to 60 minutes after ionising are very similar. However, the maximum values obtained after several days of storage show that the water in table 2 had about 50 million times more available electrons than the water in table 3, which was produced at a six times faster flow rate.

Even more striking is the comparison with table 4. Here the number of electrons is so low that the water cannot hold its charge for long. The reason why the measurements of low-ORP water do not increase much during storage is the small amount of infiltration of oxidising species with fast flows. Therefore in this case the initial measurements are a good indication of the true value, unlike with slower flows that allow much greater mixing of ions.

Other factors that may influence the ORP are the rate of flow between acid and alkaline water outlets, the time since the electrodes were last cleaned with vinegar and whether the water is collected at the beginning or near the end of an ionising cycle. Generally readings may be somewhat higher soon after vinegar cleaning and near the end of a cycle but this is not consistent.

In order to slow down the flow-rate of the alkaline water I use a very thin 4 mm alkaline outlet hose as used for oxygen masks. This then greatly increases the flow-rate of the acid water. Once I used a wide 8 mm alkaline outlet hose, the same as for the acid outlet, and the flow of the acid water became very slow. However, it had a very strong ozone-like smell.

Storing and Using Ionized Water

While most vitamins suffer losses during cooking, the rate of degradation is much higher in alkaline than in neutral conditions and even less with an acid pH. Therefore, habitually cooking with alkaline water can lead to vitamin deficiencies. This was noticed especially in some regions of England where baking soda was added to the cooking water in order to preserve the colours of vegetables. Furthermore, we need strongly acid gastric juices for proper digestion and absorption of proteins and some of the minerals and vitamins.

Individuals with weak stomach acid commonly suffer from mineral deficiencies and often have soft fingernails and poor hair quality in addition to lack of energy and other problems. Also vitamin B1 requires gastric acid for its absorption. Commonly we produce less stomach acid as we get older but even many young individuals, such as asthmatics, do not produce enough stomach acid.

Drinking alkaline water on its own does not cause a problem because the stomach does not deliberately produce more acid to neutralise it. Also the mineral density of ionised water is not very high and it is easily neutralised. A glass of water (200 ml) at a pH of 10.0 changed to pH 6.9 with the addition of 16 drops of lemon juice.

Alkaline water with a lower mineral content would require even less acid to neutralise. An observed drop in ORP with the addition of organic matter is not necessarily a disadvantage. I assume that the reacting electrons just are more tightly bound but will still be available to us after absorption.

It is different if a large amount of strongly alkaline water is combined with food, either by cooking in it or when drinking close to a meal. Then the stomach is required to produce acid to digest the food but instead the acid is partly neutralised by the alkaline water. This is not much of a problem at lower pH levels, perhaps up to a pH of 8.5 or for individuals with strong gastric acid but it may be a disadvantage for others. A safe interval between drinking strongly alkaline water and a meal is about 30 minutes before and 2 to 3 hours after the meal.

The next question involves storing ionised water to preserve its negative charge. Some of the influences on its stability are as follows. A small amount of water exposed to air loses its charge much faster than a larger volume. I measured, for instance, a charge of -328 in half a glass of water go to +6 within 7 hours. In about one litre of water from the same batch the charge was still -20 after ten hours.

Another influence is the temperature. When I heated a cup of water to boiling temperature for a few minutes it had lost all of its negative charge after cooling, while the unheated water was still about -300. However, it is not the temperature as such that causes the fast discharge, but rather the strongly speeded-up reaction of the negative charge with the oxygen in the air. In a laboratory experiment it was found that autoclaved water only lost its charge if it was exposed to air, without any air in the sample it did not discharge.

Initially I believed that refrigerating or even freezing the ionised water was required to preserve its charge for days or weeks until I found that exposure to light discharged the water. Now I store the water in brown glass bottles (200 to 750 ml) filled to the top but not touching the top, and in addition I keep them in a closed cupboard. The bottle top needs an airtight seal otherwise the water will discharge much more quickly. However, the charge in an only partly filled bottle keeps longer under refrigeration and very much longer in a frozen sample.

As mentioned before, the negative charge of water produced with a slow flow rate may still rise during storage. However, this does not mean that it is more desirable to drink stored water rather than immediately after producing it. Antioxidant properties do not increase during storage, only active oxygen species are being eliminated and it may actually be beneficial to ingest some of these.

I also found that the steel outlet pipe of the ioniser unit reduces the negative charge and even slightly lowers the pH. The degree of deterioration depends on the strength of the water flow. With a strong flow (1 minute per litre) the reduction in the charge by the steel pipe was negligible as compared to a plastic hose.

However, when I inserted a thin plastic hose into the steel pipe and collected water simultaneously from both outlets at a very low flow rate, there was a great difference. The water coming out of the plastic hose had -278, while the ORP of the water running through the steel pipe was only -170. This shows that we should not store charged water in contact with blank metal as for instance with an unprotected metal bottle top.

Negative Hydrogen

Scientific articles tend to call ionised water �Electrolyzed Reduced Water� or ERW for short. The chemical reactions during water ionisation are not well understood. I believe the main reactions to be as follows.

The negative electrode or cathode donates electrons while the positive electrode or anode accepts electrons out of the solution. In the water flowing past the electrodes positive minerals or cations, such as sodium and calcium, move towards the cathode while negative anions, such as chloride and fluoride, migrate towards the anode. Electrons emitted by the cathode are attracted by the positive charges of cations and react with them to form neutral metal atoms such as sodium or calcium.

These metal atoms are rather unstable and highly reactive. They immediately react with water molecules to form hydroxides, such as sodium hydroxide, while the surplus electron is transferred to the hydrogen ion to produce a neutral hydrogen atom. Hydrogen atoms, in turn, are also very unstable and react either with other hydrogen atoms to form hydrogen molecules, or they may accept a second electron from the cathode to complete their electron shell and become negative hydrogen ions.

Expressed in simple chemical equations, using table salt as an example, this looks as follows:

Ionic aqueous solution: NaCl� �� Na⁺� +� Cl^-

Sodium ion becomes a neutral atom by accepting electron from cathode: Na⁺� +� e^-� �� Na

Sodium atom immediately reacts with water to form sodium hydroxide by donating an electron to the hydrogen ion, which in turn becomes a hydrogen atom:

Na (Na⁺� +� e^-)� +� H₂O� �� Na⁺ OH^-� + H (H⁺ + e^-)

Hydrogen atom either combines with another hydrogen atom to form a hydrogen molecule or it accepts a second electron to form a negative hydrogen ion:

H� + H �� H₂� or� H + e^-� �� H^-

Sodium hydroxide and other common hydroxides are highly soluble except for calcium hydroxide, which starts precipitating out of calcium-rich water when the pH goes above 10. Drinking water containing hydroxide is not a problem, at least up to a pH of 10 or 11, because normally so little is present that a few drops of lemon juice or gastric acid will neutralise it.

Negative hydrogen ions are the basis for the negative potential and antioxidant properties of reduced water. They can become reasonably stable by attracting the positive hydrogen potentials of water molecules. A water molecule is a weak dipole with a negative potential at its oxygen and positive potentials at each of its hydrogen atoms. The negative hydrogen ion is now in a protective cage surrounded by probably six water molecules. I assume that in this form it can pass the intestinal wall and reach the bloodstream.

Theoretically negative hydrogen ions may also react with cations to form unstable hydrides, such as sodium hydride. These, too, may be temporarily stabilised in protective water molecule cages.� Other possibilities are the formation of negatively charged hydrated cation complexes and colloids. All of these are very unstable and likely to react with any similar unstable oxidising species present. This may account for the initial strong fluctuations in the ORP potential. Contrary to theoretical expectations, measurements have shown that reduced water is higher in dissolved oxygen than the tap water before ionising.

This model shows how important it is for sufficient minerals to be present. Fewer minerals require a slower flow rate for this process to work. However, at a slower flow rate more water molecules are being split and more hydroxyl ions as well as hydrogen atoms are being formed. This causes the reduced water to become more alkaline but does not lead to more negative hydrogen being formed. The abundance of hydrogen atoms now leads mainly to the formation of hydrogen molecules, which escape as gas bubbles.

A similar process near the anode leads to the formation of neutral hydroxyl molecules. These react with each other to form water and highly reactive oxygen atoms, which then combine to form stable oxygen molecules in addition to ozone, hydrogen peroxide and possibly other oxygen species such as hypochlorite.. It is likely that in addition also some chlorine is being formed.

Previously negative hydrogen was thought to be present only in highly heated gases but more recently it has been found that it is widespread in biological systems, including fresh (organic) fruit and vegetables. It is also relatively high in mountain streams and rainwater, especially during thunderstorms. Negative hydrogen is now thought to be the primary antioxidant of all biological systems. For an interesting site on negative hydrogen and ionised water see www.negative-hydrogen-ion.org.

Using Oxidised Water

Strongly oxidised water is used by an increasing number of hospitals in the USA as the preferred disinfectant because it is apparently cheaper, safer and more effective than conventional disinfectants in eliminating pathogenic microbes. Commonly batch ionisers are used for this purpose and the water is rather high in salt (sodium chloride).

The acid water from a through-flow ioniser is usually not strong enough as a household disinfectant but may be used on parts of the body that are infected with fungi or other microbes, we may also use it for oral hygiene.

Some Recommendations

Normally, as a user of reduced water, you do not need to be too concerned with achieving the absolute maximum antioxidant potential from your ioniser. I did this mainly to find some general rules for consistently producing high-quality reduced water. Nevertheless, you should know the approximate mineral content of your water and preferably have the ORP checked sometime after set-up and whenever there is a change in operating conditions.

There are different possibilities for doing this. Ideally you may have a local distributor of water ionisers who has the necessary instruments and can help you setting your ioniser up for optimal efficiency. Alternatively, you may find other ioniser owners in your area and share the cost of buying an ORP meter, a TDS meter and an electronic pH meter. In Australia you are looking at a combined retail price of about $ 400, see my page Resources in Australia for suppliers. You may also contact a local water treatment or testing company.

If you use municipal town water that comes mainly from river and rainwater, you can expect to have low mineral values and should consider installing a small tank to supply your ioniser with water. You may just use a 5 to 10 litre container about 1.8 to 2 m higher than the inlet of your ioniser. The container does not need to have a bottom outlet as you can siphon the water over the top. Use wide hose connections (8 mm) without any restricting taps otherwise you may need more height for a sufficiently strong water flow. You can regulate the flow with an external hose clamp.

If you do not know the mineral content of your water but suspect it to be low, you may just add 2 g or half a teaspoon of salt or better twice this amount of hydrated magnesium chloride per 10 litres of water. Otherwise add enough to get a TDS value of about 350 to 400 ppm in your water. By adding more minerals than that I did not get any higher ORPs in my tests, although that may be possible with stronger electrodes or higher flow rates.

Pure rainwater in plastic or metal tanks is very low in minerals with about 20 to 50 ppm and not suited for ionising. However, it is easy to add sufficient minerals to raise the TDS to over 300 ppm. The cheapest way of doing this is by adding salt at a rate of about 3 g per 10 litres. Assuming that the TDS was 50 ppm before, this will raise it to about 350 ppm. If you prefer to add magnesium chloride instead, you may buy a 25 kg bag of hydrated magnesium chloride (from a chemical company) and add about 4 g per 10 litres in addition to 2 g of sodium bicarbonate for a truly �unique water�.

Modified Vinegar Cleanse

If you do not have an ORP meter it is advisable to check the pH of the alkaline water or make an ORP colour test once a week. Otherwise you may just produce filtered but not ionised water without realising what is going on. This happened to me when I had not ORP-tested my water for about 2 weeks. To my surprise the ionised water had the same ORP and pH as the tap water despite all the indicator lights working, the flows between acid and alkaline water remaining normal and having done a vinegar cleanse only a week before.

As I use bore water high in calcium, I suspected that the cathode (the electrode that produces the alkaline water) was completely coated with calcium carbonate and that the normal vinegar cleanse was not sufficient under these conditions. This turned out to be correct.

If your water is high in calcium I now recommend the following procedure. Remove the alkaline outlet hose, tilt the ioniser backwards and use a large syringe to slowly inject about 20 to 40 ml of white vinegar directly into the alkaline outlet. If you have difficulty buying a large syringe from a chemist, you may also pour the vinegar through a small funnel or use a suitable spray bottle.

If you put your ear close to the alkaline outlet you can easily hear the bubbling inside. After about 10 minutes the bubbling stops and now you inject 10 to 20 ml of additional vinegar. After 5 to 10 minutes the bubbling stops again and you inject more vinegar. In this way you continue until there is no further or only very little bubbling with additional vinegar. Then do a 2-minute cleaning cycle before using the ioniser setting.

If it is badly calcified you may have to inject vinegar more than 20-times. Preferably do this regularly every 2 weeks to avoid a massive calcium build-up. Occasionally you may also perform a normal vinegar cleanse by pouring vinegar into the opened filter. As an alternative method, I have now started injecting 10 to 20 ml of vinegar just once every other day after producing my ionised water.

Since starting the new method of vinegar cleanse, my alkaline water consistently measures more than �600 mV and usually more than �700 mV immediately after producing it and the ORP is very stable.

ORP Measurements

I use a Milwaukee ORP meter, the SM 500 with an official working range of +999 to �999 mV, although it indicates up to + or � 1999 mV. Like other ORP meters it has a probe with a platinum electrode that is sensitive to the flow of electrons and a calomel electrode as a stable reference electrode.

Initially ORP testing was very frustrating as the measurements were rather erratic, partly due to the inherent instability of the ionised water but mainly because of the instability of the probes. However, eventually I learned to keep the probes sensitive and accurate. However, when measuring simultaneously with several probes results still continue to vary widely with weakly ionized water that is with readings below about �200 mV. All of the described difficulties apply only to measuring the ORP of alkaline ionised water. In conventional reducing liquids such as vitamin C solutions there is no problem with ORP probes.

Most of the eight probes that I worked with were rather slow and results consistently too low right from the time of purchase compared to a good probe used simultaneously. However, more recently I found several ways to improve electrode performance. For instance after first testing a new probe with the ORP Standard solution, ionised water then gave a reading of �136. Two other probes showed �556 and �548 mV in the same sample. After I gently cleaned the platinum wire for a few seconds with fine sandpaper it immediately read �552 mV.

However many probes are not stable and need frequent sandpapering to keep them sensitive and accurate. You can notice this by measurements starting rather low and creeping up only slowly. To give an example, a probe may start measuring at �200 and take 10 to 30 minutes to reach a highest value of -500 mV. After sensitising the probe and measuring the same sample of ionized water it may start at �450 and in 1 to 5 minutes reach a stable endpoint of �700 mV.

Another and often better way to keep your probe sensitive is by frequently immersing it for 5 to 10 minutes in strongly oxidised acid water of +800 to +1100 mV. If the water is weaker, you may keep the probe in it for longer.� One probe that I presently work with sometimes gets its best performance only after using sandpapering as well as immersion in oxidized water before measuring.

It also helps to immerse a probe for an hour in 3 or 6% hydrogen peroxide or clean the electrode tip with a cotton swab soaked in 35% hydrogen peroxide. While this tends to improve electrode performance, it is much less effective than immersion in acid water with a high positive ORP.

With batch ionisers it is generally easy to obtain acid water with a high positive ORP. With through-flow ionisers you may need to restrict the volume of the acid outflow with a clamp or by similar means and use the highest setting as well as water with a high mineral content. The high positive ORP is very stable and keeps for weeks or months in a closed bottle, which does not need to be filled to the top.

Instead of keeping probes immersed in ORP storage solution I prefer to store my probes moist in the supplied airtight plastic cap but not immersed in any liquid. Another occasional problem with probes is a black fungus growth in warm weather. You may brush this gently off with a toothbrush or with a cotton swab dipped in hydrogen peroxide.�

Some probes need very little attention while others need a lot. Frequently alternating measurements between reducing and oxidizing water seems to be good for all of them and it also keeps any fungi away. After experimenting for a while you will get a feel for the needs of your probe.

Colour Tests

Colour tests with pH paper or a liquid pH indicator are relatively cheap and usually sufficient when working with an ioniser. You may also make a simple colour test for the reducing power of your ionised water. In addition to using this test instead of an ORP meter, you may also use it with unusual results to check whether your OPP meter is still working properly. Buy some Condy�s crystals or potassium permanganate from a chemist or gardening shop.

Dissolve a tiny amount of the crystals in some water to make a deeply coloured purple solution. Fill one of two identical clear glass jars or bottles with water before ionising and the other with ionised water. With a dropper add sufficient drops of the purple solution to the non-ionised water until it appears slightly pink. Then add the same number of drops to the ionised water. Place both on a white surface and look down from the top.

The reducing potential is indicated by the time it takes for the ionised water to lose its pink colour. With a very high negative ORP of about �700 mV you notice the colour fading within a few minutes and after 10 minutes the water may be nearly clear. In contrast, with a low ORP of �100 to �200 mV you may get the first hint of a colour difference between both samples after about 30 to 60 minutes and it may take 2 to 3 hours until the ionised sample is more or less clear. You may estimate intermediate ORP values from the times of the first definite colour change and the complete discolouration of the sample.�� During this test protect the ionised sample from strong light and minimise exposure to air.�����

Batch Ionisers

These observations with through-flow ionisers generally also apply to batch ionisers. Lower mineral concentrations require longer ionising times and produce greater pH and lower ORP changes. It is advisable to use water low in calcium, otherwise the cathode soon becomes coated with calcium deposits during long ionising periods and loses its effectiveness or frequently needs to be cleaned. Furthermore, it is advisable to protect the ioniser from light during long ionising periods.

To learn more about the conditions for creating a high negative ORP I acquired a cheap batch ioniser with a volume of about 4 litres. The membrane consists of a 10 mm porous ceramic plate with the two titanium electrodes (130 x 70 mm) touching the ceramic membrane on each side. The power source is 9 V.

�My first test with bore water reached �219 mV after 10 hours and �238 after 20 hours. The ORP diminished during storage on subsequent days. A manufacturers recommendation is to add just 1 drop of lemon juice to distilled or de-ionised water. This produced a maximum ORP of �193 after 20 hours and returned to a positive ORP by the next day. The alkaline water reached a pH of 9.6; by adding 5 drops of lemon juice to a glassful the pH dropped to 7.0.

With a 12 V power pack I reached higher values and even more so with 20 V. With this I used rainwater with added magnesium chloride. A higher ppm resulted in higher ORPs, generally between �300 and �350 after 3 hours. Values continued to rise during storage to over �700 after 6 to 9 days.

However, 20 V was too much for the anode, which corroded quite noticeably. With voltages over 12 V protected anodes are required, either plated with platinum or mixed metal oxides. Alternatively, if the water is very low in chloride ions then no chlorine will be formed and no corrosion is likely to occur.�

However, the greatest improvement came when I bent the electrodes so that instead of touching the ceramic membrane, there were now several millimetres of space between membrane and electrodes. With 12 V and even 9 V I now obtained ORP values of �400 and higher after 3 hours and over �500 and �600 after 10 hours. Values continued to rise during storage to about �750 mV after 6 days. For these latest tests I used rainwater with magnesium chloride added to approximately 300 ppm.

Another and bigger batch ioniser with 10 litres volume has an anode that is protected with mixed metal oxides. With this I can use 24 V without causing corrosion. The plates are about 30 mm apart. Using rainwater with the addition of magnesium chloride and a small amount of sodium bicarbonate to 300 - 400 ppm I get over �700 mV in one hour and about �800 mV in 2 hours. Generally I add a level teaspoon of hydrated magnesium chloride and half a level teaspoon of sodium bicarbonate to 10 litres of rainwater. You may also use potassium bicarbonate instead of sodium bicarbonate.

Because of the composition of magnesium chloride with one cation and two anions, it produces acid oxidised water with an ORP of more than +1000, which can be used as a very powerful household or commercial disinfectant, however, be aware that it contains chlorine. Acid water with a lower ORP and free of chlorine can be produced by using minerals that do not contain chloride.

���� Generally, with batch ionisers short ionising times are desirable. Factors that shorten ionising times are:

�             Short distances between electrodes

�             Electrodes with large surface areas

�             High voltages

�             High electrolyte concentration.

The opposite factors require longer ionising times.

Summary

With my Masterpiece ioniser I generally prefer to use an ioniser setting of 5 (maximum), a flow rate of 3 minutes per litre and a mineral content of about 350 to 400 ppm. With this I now routinely obtain maximum ORP values of about �700 mV with which I am quite happy. When I use the batch ioniser I get �700 to �800 mV in 1 to 2 hours.� For articles on ionised water and availability of water ionisers in Australia see my page Resources in Australia. Also see the related article Living Water.

This is another in a continuing series of articles that Service Industry News is presenting on pool and spa sanitation, water balance and test methods. Although it is firmly based on sound, scientific study, it is not written as a scientific paper, but rather as a practical, understandable guide for pool and spa service technicians.

Let's get something straight from the start - ORP is not a word; it's a set of initials, like IBM or IRS or NFL.

ORP stands for Oxidation-Reduction Potential. In practical terms, it is a measurement to oxidize contaminants. It's as simple as that.

Well, then, you might ask, if ORP is so simple that it can be reduced to an 11-word definition, why are you devoting an entire article to it, and why should it be important to me at all?

The answer to that is that right now, ORP is the only practical method we have to electronically monitor sanitizer effectiveness. Every true system of automatic chemical control depends on ORP to work.

If you've been in the pool and spa service industry for any length of time, you already know the routine involved in maintaining proper water chemistry. First you test the water, then you adjust it to recommended chemical levels.

That sounds simple, too. Of course, you could make automobile maintenance sound just as simple: Simply measure the car's performance; then adjust everything necessary to make it perform the way it should.

In the real world, we all know that chemical maintenance of pool and spa water is a fairly complicated balancing act. You must maintain sanitizer residual at a level sufficient to protect swimmers and bathers from the invasion of unwanted - and possibly harmful - plant and animal life. You must maintain the pH of the water at a level that assures the sanitizer works effectively and at the same time protects the pool shell and equipment from corrosion or scaling and the bathers from discomfort or irritation.

Along the way, you must make sure that all the other ingredients in this chemical mix - total alkalinity, water hardness, temperature, and total dissolved solids (TDS), to name four big ones - are also in balance or not out of the recommended range.

But of all the factors involved in chemical maintenance, the "frontline" troops are two: sanitizer residual and pH. By far, these are the chemical tests performed most often. By far, these are things that we are most concerned with.

ORP and and pH sensors allow us to electronically monitor and control sanitizer residual and pH automatically. In a light usage residential pool, this might not be a primary concern. But in a public or semi-public pool or spa - one that is under constant observation by local health authorities - some form of dependable, accurate, automatic chemical control may well be a necessity.

"But," you might say, "I'm already in control. I've got an erosion feeder hooked up to the suction line, or a floater in the pool, or I've left chemicals behind with the owner to add between service calls. There should be plenty of sanitizer in the water by the time I return for my next call."

The key words are "dependable" and "accurate." The methods described above may get some sanitizer in the water, but will it be enough? Will it be too much? Will it get done at all?

An erosion feeder, hooked in-line with the circulation system, will dispense some chemicals whenever the system is running - whether they are needed or not. A floater will dispense some chemicals constantly - whether they are needed or not. Depending on a pool owner to take care of things between calls is - well - chancy at best and downright dangerous at worst.

Besides, erosion feeders and floaters only deal with sanitizer residual. There's still nothing there to control pH. pH, as we all know, is the thing that makes sanitizer work.

If you want true chemical control, you've got to have some method of monitoring both the sanitizer residual and the pH and using that information to chemically treat the water. That's where ORP enters the picture.

So What Exactly Is ORP?

As we stated earlier, ORP stands for Oxidation-Reduction Potential. In some parts of the world, it is also known as Redox Potential. Sometimes, you'll see the words "oxidation" and "reduction" spelled without the hyphen connecting them. We chose the hyphen because the two chemical reactions are really "joined at the hip" - one cannot occur without the other also occurring.

When chemists first used the term in the late 18th Century, the word "oxidation" meant, "to combine with oxygen." Back then, it was a pretty radical concept. Until about 200 years ago, folks were really confused about the nature of matter. It took some pretty brave chemists to prove, for example, that fire did not involve the release of some unknown, mysterious substance, but rather occurred when oxygen combined rapidly with the stuff being burned.

We can see examples of oxidation all the time in our daily lives. They occur at different speeds. When we see a piece of iron rusting, or a slice of apple turning brown, we are looking at examples of relatively slow oxidation. When we look at a fire, we are witnessing an example of rapid oxidation. We now know that oxidation involves an exchange of electrons between two atoms. The atom that loses an electron in the process is said to be "oxidized." The one that gains an electron is said to be "reduced." In picking up that extra electron, it loses the electrical energy that makes it "hungry" for more electrons.

We also know that matter can be changed, but not destroyed. You can alter its structure, and can increase or decrease the amount of energy it contains - but you can't eliminate the basis building blocks that make things what they are.

Chemicals like chlorine, bromine, and ozone are all oxidizers. It is their ability to oxidize - to "steal" electrons from other substances - that makes them good water sanitizers, because in altering the chemical makeup of unwanted plants and animals, they kill them. Then they "burn up" the remains, leaving a few harmless chemicals as the by-product.

Of course, in the process of oxidizing, all of these oxidizers are reduced - so they lose their ability to further oxidize things. They may combine with other substances in the water, or their electrical charge may simply be "used up." To make sure that the chemical process continues to the very end, you must have a high enough concentration of oxidizer in the water to do the whole job.

But how much is "enough?" That's where the term potential comes into play.

"Potential" is a word that refers to ability rather than action. We hear it all the time in sports. ("That rookie has a lot of potential - he hasn't done anything yet, but we know that he has the ability to produce.)

Potential energy is energy that is stored and ready to be put to work. It's not actually working, but we know that the energy is there if and when we need it. Another word for potential might be pressure. Blow up a balloon, and there is air pressure inside. As long as we keep the end tightly closed, the pressure remains as potential energy. Release the end, and the air inside rushes out, changing from potential (possible) energy to kinetic (in motion) energy.

In electrical terms, potential energy is measured in volts. Actual energy (current flow) is measured in amps. When you put a voltmeter across the leads of a battery, the reading you get is the difference in electrical pressure - the potential - between the two poles. This pressure represents the excess electrons present at one pole of the battery (caused, incidentally, by a chemical reaction within the battery) ready to flow to the opposite pole.

When we use the term potential in describing ORP, we are actually talking about electrical potential or voltage. We are reading the very tiny voltage generated when a metal is placed in water in the presence of oxidizing and reducing agents. These voltages give us an indication of the ability of the oxidizers in the water to keep it free from contaminants.

How Do You Measure ORP?

An ORP probe is really a millivolt meter, measuring the voltage across a circuit formed by a reference electrode constructed of silver wire (in effect, the negative pole of the circuit), and a measuring electrode constructed of a platinum band (the positive pole), with the pool water in between.

The reference electrode, usually made of silver, is surrounded by salt (electrolyte) solution that produces another tiny voltage. But the voltage produced by the reference electrode is constant and stable, so it forms a reference against which the voltage generated by the platinum measuring electrode and the oxidizers in the water may be compared.

The difference in voltage between the two electrodes is what is actually measured by the meter. Modern ORP electrodes are almost always combination electrodes, that is both electrodes are housed in one body - so it appears that it is just one "probe."

Incidentally, the meter circuitry itself must have very high impedance (resistance) in order to measure the very tiny voltages generated by the circuit.

What Does an ORP Meter Tell US?

Now that you know the basis of how an ORP meter works, let's take a look at how changes in the oxidizer level in the water will effect the measurement.

For practical purposes, oxidizing agents are the "good guys" in the water sanitation picture, reducing agents are contaminants and therefore are the "bad guys."

If we had a body of water in which the concentration of oxidizers (or oxidants as chemists are apt to say) exactly equaled the concentration of reducers (reductants), then the amount of potential generated at the measuring electrode would be exactly zero. As you might guess, the water would be in pretty sad shape, because if any additional contaminants were introduced into the water, there would be no oxidizer to handle it.

As we add oxidizer to the water, it "steals" electrons from the surface of the platinum measuring electrode. To make things a little more confusing, we need to point out that electrons are negatively charged particles. When we remove these negatively charged things from this electrode, the electrode becomes more and more positively charged. As we continue to add oxidizer to the water, the electrode generates a higher and higher positive voltage.

How pH Affects ORP

Service professionals are already well aware that sanitizer effectiveness can vary rather significantly with changes in pH - particularly in regards to chlorine, which is by far the most commonly used chemical for water sanitation.

You will recall from previous articles about chlorine that the killing form of chlorine is hypochlorous acid (chemical formula HOCI), which, not coincidentally, is a powerful oxidizer. You will also remember that the percentage of hypochlorous acid is present in pool and spa water depends directly on the pH.

For example, at a pH of 6.0, 96.5 percent of the Free Available Chlorine in the water is in the form of HOCI, while at a pH of 8.5, only 10 percent is in this active killing form.

Testing the water with OTO can tell you the concentration of chlorine, but it cannot tell you how much of the chlorine is combined into organic compounds or how much is in the form of hypochlorous acid. Changing the pH of the water will not affect the result of an OTO test.

A DPD test can tell you how much of the chlorine is combined and how much is free and available, but it cannot tell you what percentage is in the form of hypochlorous acid. To determine this, you must take a pH test and calculate the results. Altering the pH will not effect the results of a DPD test.

Although ORP does not specifically tell you the chlorine concentration in parts per million, it does indicate the effectiveness of the chlorine as an oxidizer. An ORP reading will vary as pH fluctuates. As the pH goes up, the millivolt reading on an ORP meter will go down, indicating that the sanitizer is not as effective. Bringing the pH down or adding more sanitizer will raise the millivolt reading.

That is why most ORP instruments also incorporate an electronic pH meter - which measures the difference in electrical potential between the pool water and a sample of known pH that is contained in the probe in a small glass bulb.

Setting the Standard

Once the instruments and methods for measuring ORP were developed in the 1960's, researchers began working toward setting standards under which ORP measurements could be used as an accurate gauge of water quality.

In 1972, the World Health Organization adopted an ORP standard for drinking water disinfection of 650 millivolts. That is, the WHO stated that when the oxidation-reduction potential in a body of water measures 650/1000 (about 2/3) of a volt, the sanitizer in the water is active enough to destroy harmful organisms almost instantaneously.

In Germany, which has about the strictest water quality standards in the world, an ORP level of 750 millivolts has been established as the minimum standard for public pools (1982) and spas (1984).

In its 1988 standards for commercial pools and spas, the National Spa & Pool Institute stated that ORP can be used as a "supplemental measurement of proper sanitizer activity" when chlorine or bromine are used as primary disinfectants. The recommended minimum reading under the NSPI standards is 650 millivolts, with no ideal and no maximum.

The NSPI also stated that "the use of ORP testing does not eliminate or supersede the need for testing the sanitizer level with standard kits."

The above statement is not necessarily a matter of the NSPI being cautious about setting chemical standards. The fact is that most health codes still specify that a measurable free available chlorine (FAC) residual - usually 1.0 ppm present in the water of public pools and spas, as measured with a DPD test kit.

Chemical Automation

ORP technology has received widespread application in this country as the basis of automated chemical control equipment. The reasoning is clear: Only an ORP sensor can deliver the kind of feedback needed to control feeders for sanitizer and pH adjusting chemicals.

Unlike constant feed or timer controlled devices, ORP based chemical controllers can dispense pool chemicals as they are needed. Combined with a pH sensor, these controllers can be used to activate liquid feed pumps, gas chlorinators, and erosion type feeders for dry chemicals. They also can monitor pool water chemistry and record the reading on a chart.

Clearly, this type of chemical automation can result in significant savings for operators of large, commercial pool and spa installations, because chemicals are only dispensed when they are needed.

Further, electronic control assures that sanitizer and pH adjusting chemicals will be dispensed precisely as they are needed, eliminating the peaks and valleys in sanitizer residual and pH that often occur in pools and spas as bather load fluctuates.

Control equipment is generally installed with the ORP and pH probes placed in the pressure line, or water from the pressure line may be diverted to the probes. Probes are always installed prior to the point of chemical injection. This way, water passing over the sensors is representative of water in the pool, and the sensors are always ready to produce an accurate voltage.

When used with liquid chemical feed pumps, the signals from the pH and ORP probes determine when the controller activates chemical pumps. The pumps are turned on and off to achieve the set points (desired control levels).

When using a gas chlorinator, the controller activates a solenoid valve, which permits gas to be injected through a bypass line and into the recirculation line. A booster pump in the bypass line is often used to assure adequate dispersion of gas.

Erosion feeders (dispensing trichlor or calcium hypochlorite tablets or bromine sticks or tablets) can also be controlled by an ORP controller. The feeder is placed in a bypass line, which is opened or closed through the use of a solenoid valve.

In addition, ORP devices can be used to measure sanitizer effectiveness and to control ozone generators, chlorine generators, and ionizers (in combination with chlorine).

In Conclusion...

We hope that this introductory story has helped remove some of the mystery behind oxidation-reduction potential. Those of you who service commercial pools will surely be selling more ORP based chemical controllers as time goes on, and being familiar with their theory of operation can only make you more valuable to your customers. Although so called "chemical automation" may sound like a threat to the livelihood of a pool and spa service professional, we don't think you really have anything to worry about. Even a pool equipped with every labor saving device known to man still needs someone to take care of the day to day maintenance that the pool owner doesn't want to do himself. That is the basis upon which the Service Industry was built, and we are sure that it will continue to be our strength in the future.

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