Sanitisers ~ This group of chemicals is the most important in treating your pool. Their job is to quickly kill any bacteria or viruses that get into the water so that they cannot multiply and cause infections in swimmers. Most of them contain chlorine.
Calcium Hypochlorite – an off white granule chlorine granules or tablet.
It contains 65% available chlorine and when dissolved in water it leaves some solids.
It is slightly alkaline so it will increase the pH.
It should be dosed into a skimmer or the solution can be added through a small dosing pump.
75 grams adds approximately 1 part per million of free chlorine to 10,000 gallons of water.
The level of free chlorine should be maintained at between 1 and 2 parts per million. This is measured with a chlorine (DPD 1) test kit.
When used in an outdoor pool the sunlight breaks up some of the free chlorine. So in sunny weather it may be difficult to maintain the correct level of chlorine.
It is also used as a shock treatment to rid the pool of algae or to burn off unpleasant chlorine by products (chloramines).
In order to stop chlorine being broken down by sunlight it is combined with a stabiliser – cyanuric acid.
Cyanuric acid can be added separately or more commonly it is supplied as stabilised chlorine granules or tablets.
The problem with all stabilised chlorine products is that as well as stopping the sunlight breaking down the chlorine they also make the chlorine less effective. Therefore it is important not to get too much cyanuric acid in the water.
The cyanuric acid level can be tested with a test kit. The only way of getting rid of cyanuric acid is by dumping water.
There are two forms of stabilised chlorine
Stabilised Chlorine Tablets (sodium dichloroisocyanurate) – This is a white tablet which adds chlorine to the water just like any other sanitiser but it also adds stabiliser at the same time. It has a pH close to neutral (7) so that it will have little effect on the pH of the pool water. It is added by dissolving the required quantity in warm water. 60 grams will add 1 part per million chlorine to each 45 cubic metres (10,000 gallons) of pool water.
Stabilised Chlorine (Trichloro isocyanuric acid) – This is normally supplied as a 200 gram tablet which adds chlorine to the water just like any other sanitiser but it also adds stabiliser at the same time. It is acidic so it will reduce the pH of the pool water making it necessary to add an alkalinity builder to the water to prevent corrosion or the attack of concrete or tile grout. The tablets are slow dissolving. They are usually put in the skimmer to dissolve over several days. One 200 gram tablet will add approximately 4 parts per million of chlorine to each 45 cubic metres (10,000 gallons) of pool water, this might seem a lot in a small pool but remember, it is dissolving slowly
Hint: Add Chlorine in the evening instead of the morning, as this can halve your chemical costs.
Why? At night, chlorine is used up doing useful work in your pool, like oxidizing all the sweat and sun-tan lotion from your pool party. During the day, it is mostly wasted — lost to the UV in the sunlight. Depending on stabilizer levels, and sunshine, you can lose half the chlorine in the pool in as little as 30 minutes! Even when your swimming pool is stabilized, you can lose half the sanitizer in 4 hours. But, at night, all of the chlorine used is doing something useful to your pool water!
Some pools are fitted with circulation feeders called brominators.
These use a sanitiser called bromo-chloro-dimethyl hydantoin (BCDMH).
BCDMH is supplied in the form of white tablets which are loaded into the brominator and the pool water is pumped over them.
BCDMH should not be added directly to the pool or through the skimmers.
The level of active bromine in the pool is tested with a bromine test kit and the brominator is adjusted to give a bromine level between 2 and 4 ppm. The pH level can be allowed to rise to between 7.8 and 8.0 so very little pH minus is required.
As the chlorine and bromine in BCDMH are used up the amount of the DMH part of the chemical in the pool increases. Excessive DMH affects the disinfection efficiency so the level must not be allowed to get too high. The concentration should not exceed 200 ppm.
Apart from the higher free bromine and pH levels all the other pool parameters such as alkalinity and calcium hardness are the same as in chlorinated pools.
Give us a call at 480-222-0895 for all your pool maintenance needs in Scottsdale, AZ.