Major pertinent properties

pH

This is the first property, pH is a measure of whether pool water is acid or alkaline. Strictly speaking, pH is the negative logarithm of the hydrogen ion concentration measured in gram atoms per litre, and although the pH scale ranges from zero to fourteen, swimming pool water is normally in the 6.8 to 8.6 range, and for some very important reasons.

When the pH range is below 6.8 - that is, when the water is acid, many unpleasant things start to occur. Swimmers suffer skin discomfort and eye irritation, metal pool equipment corrodes, and vinyl liners become wrinkled. Also, in water of a low pH level, there is excessive loss of chlorine sanitizers.

On the other hand Water at a pH above 7.6 creates other kinds of problems. High pH promotes scale formation and causes cloudy water. The efficiency of the aligator and the chlorine are both adversely affected and will lose their effect progressively as the pH rises.

Another very important fact to remember about a pH scale is that it is not a straight line mathematical function, but logarithmic.

This means that a pH of 2 is one hundred thousand times more acid than a pH of 7, and a pH of thirteen is one million times more alkaline than a pH of 7. This gives some idea of the magnitude of the impact which a "too high" or a "too low" pH can have. But happily, pool water pH can be controlled, and without too much difficulty.

To lower the pH we recommend Sodium Bisulphate (dry acid).

To raise the pH we recommend the use of Sodium Carbonate (soda ash) for marbelite pools only. For pools constructed of Vinyl or plastics of any type we recommend Bicarbonate of Soda also known as Sodium Bicarb. Please see qualities tables for the correct amounts.

Another reason for our concern about the pH position is its effect on hypochlorous acid. Put into water every chlorine sanitizer hydrolyses to form hypochlorous acid. This is the active ingredient which destroys bacteria, viruses and algae, as well as eliminating unpleasant odours and organic matter.

The ideal range pH range is 7.0 to 7.4. At this setting the hypochlorous acid and the hypochlorite ions are at approximately a 50 : 50 ratio. This puts the hypochlorous acid at the right strength to act ac a safe and effective killing agent. A high pH of 8.5 reduces the hypochlorous acid to 10 per cent seriously reducing its effectiveness as a sanitizer. The aligator is effected in exactly the same way. Alternatively, a low pH of 6.5 increases the hypochlorous acid to 90 per cent. The water can be crystal clear giving a false impression that the pool is correct. However at this strength, the water is very aggressive and will attack everything, people and pool included.

alkalinity

The second key property is total alkalinity. alkalinity is the mix of bicarbonates, carbonates, and hydroxides in the water. More to the point is a measure of the waters buffering capacity. This is the waters degree of resistance when it comes to moving the pH into the ideal range.

It is very difficult to adjust the pH of water with a high alkalinity as the degree of resistance is reminiscent of a car trying to enter a garage with the doors closed. The car will get through only after much effort. On the other hand, when the water has a low alkalinity, the reverse situation occurs. Meaning the slightest addition of chemicals or debris will change the pH.

Extreme alkalinity’s also cause pool deterioration. High alkalinity forms the calcium scales all to familiar to pool owners. On the other hand a low alkalinity makes the water aggressive. It attacks the pool, etching plaster and tile grouting and corroding metal fixtures. It will also cause the premature erosion of the aligator's electrodes.

But alkalinity, like pH can be controlled. It can be kept between the desired range of 90 to 140 parts per million of calcium carbonate.

Note: calcium carbonate is only one of the three alkalinity components, but is the only one used to determine the desired range.

To lower the alkalinity we recommend Sodium Bisulphate (dry acid)

See quantities table for the correct amounts.

To increase alkalinity we recommend Sodium Bisulphate for all pools. We do not recommend Soda Ash. See quantities tables for the correct amount.

The aligator will sanitize your pool correctly and will allow you to run the pool with only 0.6 ppm to 0.8ppm of Chlorine present, making the pool much more stable and considerably less harmful to you and the environment.

Winterisation of Outdoor Pools

The information contained herewith is intended to be a guide to assist operators of outdoor pools in temperate climates [not tropical] to close their pools down for the winter in the most economical way.

In issuing this guide, aligator does not and will not, be held responsible for any problems occurring due to its implementation.

1. Clean all debris and dirt from the pool.
2. Backwash the filter until the sight glass is absolutely clear.
3. Top up pool to its normal level.
4. Bring the pH to 7.0.
5. With the pump set on filter, shock treat the pool according to the instructions given earlier Re-test the pH and adjust. if necessary.
6. Set pump on BYPASS/CIRCULATE and leave on this setting.
7. Set timer on pump/aligator to 4 hours on and 8 hours off.
8. During the course of the winter, periodic checks and corrections of the pH should be made and debris cleaned from the pool. If it is necessary to use the vacuum, the pump should be set on waste and not on filter, after which the pool should be topped up to its normal level. Reset the pump to bypass/circulate after cleansing operation is complete.

Note: Once the above operation has been completed the pool is NOT suitable for bathers.

Test Kits

There are a number of test kits on the market all of which have their own instructions in their use. For the successful operation of the aligator you need to be able to test for:

• pH
• Alkalinity
• Chlorine

In addition a cyanuric test kit is advisable. pH and Chlorine test kits alone are not sufficient for good management.

Test kits in good condition are vital for the good management of your pool.

Test kits should be kept in a cool place away from direct sunlight. The chemicals and tablets contained therein should not be more than one year old as they deteriorate with age, so they should be updated frequently.

Note: If you have a defective test kit you will never achieve good management of your pool. The best advise we offer to all pool owners is to

KNOW YOUR OWN POOL

Know the chemical requirement and have a very regular pool cleaning and maintenance programme.

We wish you many happy hours of healthy swimming.