Quote Originally Posted by BigDave View Post
You're right! You haven't been raising (or keeping) your chorine levels high enough. Not nearly high enough to battle mustard algae. Please see Ben's Best Guess Chart for reference.

I have a problem with the CYA level of 100ppm. 100ppm is the top reading of most CYA tests so your actual value could be higher. You can use the dilution method to verify: mix 1 part pool water and one part tap water (tap has no CYA), test the mix for CYA and multiply the result by 2.

How are you testing? We recommend the Taylor K-2006, you may want to consider the K-2006C, it has 2oz reagent bottles insted of 3/4oz, you'll use alot with the FC levels you're going to need to test. If you purchase through this link: Taylor Service Complete Pool Water Test Kit K-2006C, the PoolForum gets a commission to help keep the lights on.

The FAS-DPD test is the only way you'll be able to manage the process of cleaning your pool and the Taylor K-2006 is the only readily available kit that has it. Accept no substitutes!
thanks for your help. If I were to use my granulated triclor 99% to bring my CL levels up high enough to kill it, how much in weight/volume should I add to a 21,000 gallon pool. i cant seem to find a calculator for the powder.