What is Algae?
Algae are microscopic forms of plant life and there are many thousands of species. Most commonly green or brown in appearance, they grow in the presence of sunlight. Algal growth may be noticed first as a green or brown stain on pool steps, surfaces, or as a greenish tinge in the water. Left unchecked, algae multiply quickly causing considerable problems such as cloudy and discoursed water, blocked filters, increased chlorine demand, and hazardous, slippery surfaces.
Will Chlorine kill Algae?
Yes, normally, but there are occasions when Chlorine levels are too low or the Chlorine is not acting effectively because the water is out of balance. There also could be high levels of Chlorine stabiliser present in the water, reducing the 'kill time'. Some strains of algae are also resistant to Chlorine.
What can I do to prevent Algae from forming?
Ensure that there is adequate Chlorine in the pool at all times, even when the pool is not being used. To back up the Chlorine, use a long life Algaecide when the pool is opened and, if necessary, during the swimming season. An All Year Algaecide would be recommended for this particular type of application.
What is calcium hardness?
It is a measure of the amount of dissolved calcium salts in water.
What happens if my calcium levels are too low?
The water becomes 'calcium hungry' and if there is not enough dissolved calcium in the water it will try to take it from other parts of the pool structure, e.g. grouting and other concrete surfaces.
What happens if my calcium levels are too high?
If the Calcium is not dissolved, it may appear as particles in the water leading to milky, cloudy water. These particles, if left long enough, may form scale on pool surfaces and your pipes and fittings.
Should I be concerned if calcium levels are high?
Calcium levels are not a major concern, unless there are also high levels of pH and alkalinity, combined with high water temperatures.
What should be the correct level of calcium hardness in my pool?
Calcium levels should be above 200 ppm and below 1,000 ppm.
How often should I test for calcium hardness in my pool water?
Once every six weeks.
How do I carry out a test for calcium hardness?
Test Calcium Hardness level using a specified test strip. If the Calcium Hardness is below 200 ppm, add A Water Hardener, following the directions on the container. If the Calcium Hardness is above 1,000 ppm, partially replace the pool water with fresh water.
What is Combined Chlorine?
Combined Chlorine is free chlorine that has been used up and combined its self with the waste products. They are formed when the chlorine attacks/oxidises organic matter ie Algae, bacteria to form Chloramines. (These are poor disinfectants and give rise to odours and irritation).
Can I measure Combined Chlorine in my swimming pool?
Yes. The Total Chlorine minus Free Chlorine equals the Combined Chlorine.
To check Total Chlorine, add a DPD No.3 Test Tablet after the Free Chlorine test. Allow to stand for 2 minutes, then read. Subtracting the Free Chlorine reading from the Total Chlorine reading will give the Combined Chlorine.
Apart from having sore eyes etc, how do I know if my Combined Chlorine levels are excessive?
The Free Chlorine level should be at least twice the level of Combined Chlorine, and Combined Chlorine should always be below 1 ppm.
How do I reduce Combined Chlorine?
Shock dose. Shock dose means to dose with Free Chlorine up to about 10 ppm.
Can I use chlorine granules to shock dose?
When you use Chlorine Granule they normally contain an in-built stabiliser designed to release Chlorine slowly over a period of time. The advantage of a shock Chlorine Granule is that it releases Free Chlorine as soon as it has dissolved.
How frequently should I use a Shock Chlorine Granule to shock dose?
Whenever Combined Chlorine levels are too high.
How do I test Combined Chlorine?
Using a Pooltester that is filled with the swimming pool water to enable you to drop a DPD No. 3 tablet into the cell you can use if you test for Free Chlorine - the sample containing the pool water reacted with a DPD no 1 tablet. Allow to stand two minutes and match the colour with the standard. This will give you the Total Chlorine. Subtract the Free Chlorine from the Total Chlorine to give you the Combined Chlorine level. If the Combined level is too high, shock dose the pool using unstabilised Chlorine Granules.
What if I can smell a strong chlorine odour in my pool?
You may have been lead to believe that there is too much Chlorine in the water. In fact it is quite the opposite what you can actually smell is Combined Chlorine and there is not enough free chlorine to 'burn out' the chloramines.
How can I eliminate the chlorine odour?
Adjust the pH to 7.2 - 7.4 and raise the free chlorine level in the pool to at least twice that of your combined chlorine level(DPD No3) with a Chlorine Shock Granule, following the instructions on the container.
What is a chlorine stabilizer?
The chemical name for Chlorine Stabiliser is Cyanuric Acid. Cyanuric Acid protects the free chlorine in outdoor pools from sunlight which will destroy it.
Do all chlorines contain stabilizer?
Not all chlorine whether granule, tablet or liquid contain stabalisers. If you are using these products to sanitise an outdoor pool, you will reduce your chemical costs by adding a Chlorine Stabiliser to the water.
How much chlorine stabilizer do I need to protect the chlorine in my pool?
The minimum level to stabilise Chlorine is around 30 ppm.
Can I have too much stabilizer in my pool water?
Yes. Too much Stabiliser slows down the time it takes for the Chlorine to do its job. To compensate for this, you would need to run the pool at higher levels of Chlorine to achieve the same 'kill rate'. In extreme cases, high levels will result in prevention of Chlorine effectiveness, resulting in cloudy water.
What would be the maximum level of stabiliser for my pool?
Attitudes vary, but most would agree that the effectiveness of the Chlorine may be impaired at around 130 - 160 ppm. You should not allow levels to exceed 200 ppm, which is widely accepted as the maximum limit.
How often should I test for cyanuric acid?
At least once a month during the swimming season.
How do I test for cyanuric acid?
An inexpensive test is the 'disappearing dot' Cyanuric Acid test kit*, available from your nearest Stockist. The test kit comes with 'easy-to-use' operating instructions. If you need to raise the Cyanuric Acid level to 30 ppm, add a Chlorine Stabiliser following the directions on the container label.
How can I reduce the cyanuric acid level in my pool?
There is no chemical that will achieve this. The only practicable way to reduce levels is to partially drain the pool and top it up with fresh water. Do this in stages so as to avoid putting unnecessary strain on the pool structure.
What has caused my pool to go cloudy?
Cloudy water can be caused by several different water conditions: high pH, high total alkalinity, high combined chlorine, algae growth, poor filtration, or bacteria.
What should I do if my pool water is cloudy?
Carry out the following:
What should I do if the cloudy water doesn't clear?
Carry out the following:
What causes my eyes to itch and/or my skin to irritate?
There are three possible causes - use your Pooltester test kit to see which is the most probable.
What do I do if eye irritation occurs?
Check the results of your tests:
What is Free Chlorine?
Free Chlorine is the amount of chlorine in the pool after dealing with any demand on it from organics already in the water.
How does Chlorine kill bacteria?
By oxidising them. Oxidising means combining with oxygen as, for example, when a substance burns or rusts. Free Chlorine oxidises or burns bacteria.
What Free Chlorine levels do I need in my pool?
The Free Chlorine in your pool should be 1.5 - 4.0 parts per million (ppm) at all times, even when the pool is not being used.
Why should the Free Chlorine be at those levels?
Below 1.5 ppm there is not enough Chlorine to kill bacteria and algae, and there is a danger of bacteria multiplying. Higher levels than 5 ppm can lead to bather discomfort.
How often should I test the Free Chlorine levels in my pool?
During the swimming season, this should be done daily, whether the pool is used or not.
How do I test the Free Chlorine in my pool?
Using a suitable Pooltester, dissolve a DPD No. 1 tablet in the pool water sample. Note the colour change in the sample and take the reading by matching the colour of the sample with the DPD colour standard. If the Free Available Chlorine is below 1.5 ppm, add the Chlorine Granules. If the Free Available Chlorine is too high for safe bathing (above 10 ppm), add a Chlorine Neutraliser such as hydrochloric acid.
What should I do if, when testing for Free Chlorine, the sample remains clear?
If your sample remains clear, it may indicate a very low Chlorine level, or a residual in excess of 10 ppm. If high Chlorine levels are suspected, re-test, watching the test tablet closely. A pink flash around the DPD No.1 test tablet may indicate a high Chlorine level. To gain a more accurate reading, dilute the sample with mains water and multiply the reading by the dilution factor.
Why did my pool water go green?
At some stage, chlorine levels may have fallen or the Chlorine has become ineffective. The algae will then be allowed to become established.
How do I eliminate the algae?
Take the following action:
PH What is PH?
It is a measure of how acid or how alkaline your pool water is. By way of example, vinegar and cooking apples are sour, they are acidic and have a low pH value Baking soda and chalk are alkaline and have a high pH value.
How is PH measured?
pH is measured on a scale of 0 (very acidic) to 14 (extremely alkaline). 7.0 is the neutral point.
What should the pH of my pool water be?
Between 7.2 and 7.6. The human body is most comfortable at a pH of around 7.4.
What affects the pH of my pool water?
Mains water introduced into the pool can affect pH because of its salts and mineral content, gathered naturally or on its journey to reservoirs. The type of sanitiser/chlorine, or other chemicals used will also affect the pH levels.
How often should I check the pH?
Preferably daily but a least once a week.
How do I test for pH?
Using a suitable Pooltester, dissolve a phenol red tablet in the pool water sample and take the reading by matching the colour of the sample with the colour on the test kit. If the pH is below 7.2, add an Alkali. If the pH is above 7.6, add a Dry Acid. As always, following the directions on the container.
Too much chlorine? What happens if there's too much chlorine in my pool?
Too much Chlorine may cause bleached hair, bleached swimsuits, and possible eye irritation.
What should I do if I have too much chlorine in my pool?
Stop adding Chlorine until the Free Chlorine level is 1.5 - 4.0 ppm.
What should I do if the Free Chlorine is more than 10ppm?
When Free Chlorine levels are more than 10 ppm, add a suitable Chlorine Neutraliser to reduce the chlorine level.
Note: - You should not use the pool if the Free Chlorine is above 10 ppm.
What is total alkalinity?
Total Alkalinity is a measure of the amount of bicarbonates and carbonates in pool water.
Why is it different from pH?
The two are inter-related. pH is a scale measuring whether the water is acidic or alkaline; Total Alkalinity is the quantity of alkalis present in the water.
What is the correct amount of Total Alkalinity for my pool?
It should be between 100 and 160 ppm.
Why should I pay close attention to alkalinity levels in my pool?
Correct Alkalinity gives you better control of pH levels. Low Alkalinity can lead to rapid fluctuations of pH; High Alkalinity makes it difficult to raise or lower pH.
What also can happen if alkalinity is outside the recommended levels?
Low Alkalinity may also lead to corrosion and cause damage to the pool fabric and equipment. Total Alkalinity above 180 ppm may also cause cloudy water or scale formation, especially if the pH is high.
How often should I test for Total Alkalinity?
Test Total Alkalinity at least once a month.
How should I test for Total Alkalinity?
Using a suitable Pooltester. If the Total Alkalinity is below 100 ppm, add a pH Stabiliser Granule. If the Total Alkalinity is above 200 ppm, reduce the level using a suitable TA Reducer, following the instructions on the pack.