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Keeping your Pool Clean
Keeping your pool clean is an important aspect of pool maintenance and health. Untreated, or improperly treated pool water can be a health threat. Chemically balanced and sanitized water, on the other hand, will provide a healthy and visually appealing environment for you, your family and friends. Use this as information only. We always recommend consulting a swimming pool professional to ensure the safe use of your swimming pool.
Use this as information only. We always recommend consulting a swimming pool professional to ensure the safe use of your swimming pool.
Why Sanitise The Pool?
Pool water is contaminated with algae and bacteria from a variety of sources, including the air, top-up water, and swimmers. Controlling these influences is an ongoing requirement and involves:
• Chemically balancing the water to ensure it is neutral to bathers, the Pool itself, and pool equipment.
• Sanitizing the water to oxidize contaminants
Keeping your pool clean includes regular testing and balancing of your water. It takes very little time and ensures that all is well with the pool water. The following sections deal with each of these requirements and form an easy maintenance program.
Water Balance
Your swimming pool is a water container and the water it contains must be suitable for both the swimmers and the pool.
Balanced water means that its chemical demands have been met and is an important aspect of keeping your pool clean. If the chemical levels are too low the water may aggressively seek the products it needs by attacking the pool surface and equipment. This may lead to severe corrosion problems. At the other end of the scale, high chemical levels may cause chemicals to precipitate from the water and form scale on the pool surface, within equipment etc.
Out of balance water can, therefore, cause expensive damage to the pool and may also inhibit the sanitizing process.
In simple terms, a scientific water balance program suggests that the pool owner should balance the following variables:
- pH
- Total Alkalinity
- Calcium Hardness
pH
pH is a measure of how acidic or alkaline the water is. The pH scale ranges from 0 to 14, with 7 being neutral. Values below 7 are acidic and values above 7 are alkaline.pH is another improtant aspect of keeping your pool clean.
With pool water, we are seeking a pH balance suitable to the swimmers; the pool and the sanitizer used. Australian Standard 3633 defines the operating range as 7.0 to 7.8, ( 7.0 to 7.2 for fiberglass pools and 7.4 to 7.8 for concrete pools).
Topping up your pool, heavy rain, heavy bathing loads and chemical additions can all change the pH level of your pool water. pH must be kept within the operating range because if it is too high or too low it may:
- Create swimmer discomfort (itchy skin, red eyes etc.)
- Interfere with the sterilizing action of your pool sanitizer.
- Cause damage to the pool surface.
- Damage the pool equipment
pH is one of the most important aspects of your pool maintenance program.
The Effect Of pH On Chlorine
Effective sanitizing relies on pH values. Therefore, sanitizer and pH levels should be the measures you check and adjust most often.
Regardless of the chlorine type or chlorination process you use, any pH drift outside the recommended range will inhibit the sanitizing effect of your chlorine. For example, a pH level of 8.2 would mean only about 16% of your chlorine would be available to sanitize the water at any time, which means that you would have to add more than 5 times as much chlorine to achieve the same sanitizing effect. When the pH is lower than 7.0 the chlorine becomes extremely active and is rapidly consumed.
Total Alkalinity (T.A.)
This is a measure of bicarbonates, carbonates, and hydroxides in your water.
Recommended range is 60 to 200 parts per million (ppm) according to Australian Standards 3633.
Low T.A will lead to erosion of the surface of concrete and painted pools as the water takes the chemicals it needs from rendered pool-walls. Low levels will also cause the pH levels to be very unstable with small additions of chemicals resulting in major shifts in the pH values. This is sometimes known as “pH bounce”. Your Total Alkalinity levels can be changed in the following ways:
Adding “buffer” (i.e. bicarbonate of soda). This is used to RAISE Total Alkalinity.
Adding acid to your pool to lower pH will LOWER Total Alkalinity
Adding top-up water to your pool will change the Total Alkalinity depending on the TA. Of the top-up water.
The interconnection Between pH And Total Alkalinity
From the last section, it can be seen that acids will lower the pH and TOTAL Alkalinity. There is an interconnection between these two chemical components and, because of this, they need to be adjusted together. The levels you are seeking to maintain are:
pH of 7.2 to 7.8 (7.0 to 7.2 for fiberglass pools and 7.4 to 7.8 for concrete pools)
Total Alkalinity of about 100 ppm or as directed by your pool builder.
Let’s have a look at the interconnection. Assume that the pH is O.K. but the Total Alkalinity is low. To raise the level, add “Buffer” (Sodium Bicarbonate) at the required rate. However, Buffer is an alkali and will also raise the pH. Acid, which is used to lower pH, also lowers Total Alkalinity.
The trick is, therefore, to raise the Total Alkalinity artificially high so that when the acid is added to lower the pH to the correct range, the Total Alkalinity is also reduced to the correct range.
Three acid types are used to lower pH. Hydrochloric Acid, Sulphuric Acid (non-fume acid) and Dry Acid (sodium Bisulphate). All will effectively lower the pH and Total Alkalinity.
If using Hydrochloric Acid to lower pH it is vital that it be diluted (one part of acid to ten parts of water) prior to adding to the pool. Note that the filter should be running during addition and for one hour after to ensure adequate mixing.
No other type of acid should ever be used for pH or Total Alkalinity adjustment.
Always brush the pool surface immediately after adding acid.
Never mix pool chemicals of any type together.
NOTE: Always add chemicals slowly into the water. NEVER add water to chemicals.
Broadcasting chemicals inadvertently into the pool may cause surface damage and void your warranties.
Calcium Hardness
In simple terms, this measures the amount of dissolved calcium in your pool water.
The desired range is 80 to 500 ppm according to Australian Standards 3633. You should consult your pool builder or pool shop for the specific requirements of your pool finish, water supply, and equipment.
Both Total Alkalinity and Calcium Hardness need to be brought into balance. Low levels will mean that the water is corrosive to the pool and/or equipment; whereas high levels will lead to scale formation on the pool and equipment.
Measurement of Calcium Hardness cannot be performed with a normal pool test kit. We suggest that a water sample is taken to an Accredited Pool Shop for testing. Generally, in areas where calcium levels are not naturally high, testing annually will suffice after the initial adjustment. The only qualification to this is if you use Calcium Hypochlorite (65% Chlorine) to sanitize your pool. Depending upon the method used, this chemical can quickly raise Calcium Hardness levels and may require more frequent testing and adjustment.
Sanitizer
Chlorine is the most commonly used water sanitizer in the world. There are many forms of this highly effective product, including:
- Calcium hypochlorite (56% active granular chlorine)
- Sodium hypochlorite (liquid chlorine, 10-15% active)
- Stabilized chlorine (chlorine in two forms) –“DICHLOR” granular chlorine approx. 60% active and “TRICHLOR” slow dissolving tablets approx. 90% active
- Salt Water Chlorinators – these units produce chlorine through the electrolysis of salt in the pool water.
Whichever form of chlorine you use, in order for it to work, the pH is required to be in the correct range, with sufficient quantities of chlorine. Recommendations for chlorine are:
(a) at least 1.5 parts per million of Free Available Chlorine (F.A.C.) in an unstabilised pool or
(b) at least 3 parts per million F.A.C. in a stabilized pool.
To check Free Available Chlorine use a DPD test kit.
Refer to the manufacturer’s instructions to correctly and safely dose your pool with chlorine or other sanitizers.
Stabiliser
Ultra-violet light attacks chlorine. Stabilizing pool water involves adding the chemical Cyanuric Acid pool stabilizer which reduces the amount of chlorine destroyed by sunlight. Up to 5 ppm of free available chlorine can be destroyed in three hours in strong sunlight.
For health and financial reasons, it is important to overcome this effect as much as possible and so stabilizing the water is strongly recommended.
For the initial stabilizing of a new pool, Cyanuric Acid should be added to achieve the recommended level of 30 to 50 ppm.
Stabilizer is lost through splash-out and backwashing of the filter, and will need to be replaced, especially during the swimming season. To do this it is necessary to first test for the residual levels in the water.
Pool Shops or service person can do this testing from a water sample and, based on your pool volume, tell you how much stabilizer to add.
As you only need stabilizer in the warmer months, adjust the level at the beginning of the swimming season and
Check it every few months during the season. If you have to pump out water or lose a lot through splash-out and backwashing, more frequent testing and adjusting may be required.
Chemical Additions
Usually, your are far better off adding small amounts of chemicals, running the filter and testing the effects after several hours. Attempting LARGE chemical changes by adding LARGE amounts of chemicals can result in LARGE PROBLEMS.
We recommend treating one chemical problem at a time as some chemicals will react with each other and nullify their effect. Remember previous advice – NEVER mix chemicals and always add chemicals to the water.
WARNING: Failure to maintain the pool water within the recommended chemical parameters will void all warranties on the pool surface.
Please contact us for more info and advise on maintaining your swimming pool water.
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