written by Pat O’Keefe, owner of E-Z Test Pool Supplies, Inc.
A quality chlorine tablet; 99% available and 1% inert qualifies as quality tablet. Always read your label. Generally speaking, one tablet treats 5000 gallons of pool water, so
If you have a 20,000 gallon pool you will use on average 4 chlorine tablets per week.
Chlorine use is a function of temperature and bather load. If it is hot and there are a lot of people in the pool your chlorine consumption will rise dramatically. 90 degree days or heat waves will require you to add additional chlorine based upon your test result. A 20,000 gallon pool may have to go to 6-8 tabs because of heat, pool use, and water temperature.
How often should I shock my pool?
I recommend at least 1 time every 2 weeks. Once a week is clearly preferable to prevent algae growth. Greater than 2 weeks and the water quality will drop and algae growth will begin.
How much Shock should I use?
1 gallon of liquid shock per 10,000 gallons of pool water. Watch the labeling and look for 12.5% sodium hypochlorite. Note that many stores sell 8-10% in order to cut the price. In other words it is a good deal for the store but a bad deal for the consumer. A 20,000 gallon pool would use 2 gallons.
You can also use bags of shock as well. Once again be careful to read the label. We sell a TKO shock from Optima where 1 bag treats 15,000 gallons of water. Why? TKO is a fast-acting, quick dissolving multi-purpose granular that sanitizes, clarifies, prevents algae and shock treats your pool. This bag shock contains 73% available calcium hypochlorite. Reading the label is key, as not all bags of shock are created equal!
Large box stores carry bags of shock that have 50% available calcium hypochlorite. The state fire laws prevent them from stocking in their stores anything greater than 50% calcium hypochlorite. They sell their bags for less because they are giving the consumer less. When you purchase bag or bottled chlorine shock from us at E-Z Test Pool Supplies Inc., you get a higher concentrated, better-formulated product.