My brother in law has had his house with pool for a year now. Was using tablets to balance it. Calls me up last week in a panic because it's now green. I bring my trusty TF100 tester over and his CYA was something ridiculous like 120-130. Couldn't tell exactly because the test vial didn't go that high. I have him convinced to use the BBB method I learned on here.
Today the pH was 7.8 and the FC was 9. We add some muriatic acid and bring the pH down to 7.5. So now we are ready to shock it. Am I correct in my math that he will need close to 1,800 ounces of bleach to reach a shock level? I found the CYA to FC level chart on here and the highest CYA listed was 100. The shock level for that is 39. If he is at the CYA level of 120, would 45 be an accuarate guess for shocking? I just want to make sure I am steering him the right direction. His pool is a plaster in ground, about 24,000 gallons.
Thanks for the help.