Algae, Chlorine Levels and Bleach

[Watermom]

In a 22.5K pool, each quart of 6% bleach will add approximately 0.7ppm of chlorine.

[CarlD]

If you cannot find the calculator, the rule of thumb is:
1 gallon of bleach will add the same number of its concentration to 10,000 gallons. IOW, 1 gallon of 6% adds 6ppm to 10,000 gallons. 1 gallon of 12.5% adds 12.5ppm to 10,000 gallons. So for 20,000 gallons you need twice as much.

The underlying formula used in all bleach calculators is:
(1,000,000/Pool Vol in Gallons) * (Bleach Concentration) * (# of gallons of bleach) = FC added in PPM.

Bleach concentration is a decimal, so 6% is 0.06. 5.25% is 0.0525, 12.5% is 0.125.

For people who measure their pool in liters and buy bleach in liters, simply replace liters wherever I have gallons.

Carl

[cathy]

Great - so I emptied about 1/3 of my pool water (didn't want to risk my liner by emptying more than that - over time it has pulled away from the sides in a couple places). My CYA is still 100 so it must have been higher than that before. :-(

I turned off my chlorinator and started dumping in the bleach. How many hours must I wait to check my chlorine levels again? I want to keep it at 25 so the water clears quicker.

Thinking a lot of people are reading your site - big stores are running low on bleach! Thanks!

[Watermom]

You can check the chlorine levels 2 or 3 hours after adding bleach. You are right that the more consistent you can maintain shock level, the faster it will clear. 100 is still pretty high for cya, and actually, since most tests can't differentiate any higher than 100, it still could be higher than that. You can either do another partial drain and refill or just be diligent about running higher than normal chlorine levels after you get this cleaned up. You'll probably have to clean your cartridge frequently. Take some pictures so you can see improvement. One day when it is all clear and you look back at the pictures you'll be amazed at what bleach did for your pool!