If you can not seem to ever get a chlorine reading or keep chlorine in the water there could be a number of reasons which cause this to occur.
If the filtration system is not working as it should to remove the small particles from the water the chlorine demand is increased, therefore check your filter to make sure it is running at its optimum.
If your pool water is exposed to the sun you would find it difficult to maintain a chlorine residual without stabiliser. Stabiliser is a product that protects chlorine from the sun. Working like a sun-screen, it keeps the chlorine in the water longer and therefore helps to keep a constant chlorine residual. To check your pool contains enough stabiliser to carry out this function, bring in a water sample to us and we will check it for you FREE.
Sometimes, if you have too much "used up" chlorine, it can make it difficult for the free chlorine to sanitise, therefore causing the chlorine residual to be low. This can be removed by simply shocking or ozidising the pool water. BioGuard LITE or for salt pools BioGuard Salt Pool Sparkle are very effective in removing the 'used up' chlorine from the water.
Keep in mind that if your water contains too much chlorine it can bleach the tablet causing a false zero (0) reading. If you suspect this, dilute your water sample with fresh water. If you get a pink reading in the diluted sample it means there is too much chlorine in the water.