Please check my math

[HeliRN]

I am pretty sure I have mustard algae and plan on treating it myself instead of letting the pool store sell me $100 worth of chemicals. Recently bought a Taylor kit and got the following results-
25,000 gallons swg
3.5 FC
0.5 CC
35 CYA
7.8 PH
70-80 total alk
I bought 10% bleach and believe I need 4.5 gallons to get FC to 21 for mustard algae? First time treating it myself and want to make sure i do it right. Thanks

 

[Richard320]

You did it right. However, the CYA scale is not equidistant, so we round up. Call CYA 40 and Mustard Shock goes to 24. That's 5.1 jugs for the first dose. Fix the pH first. You won't be able to test it for a few days and bleach works better at lower pH besides.

 

[HeliRN]

Ok thanks! Approximately how long will I need the chlorine level this high and continue to add bleach? I know I need it to pass the 3 tests, but do I do the overnight test the first night or does it usually take several days?

 

[Richard320]

Ok thanks! Approximately how long will I need the chlorine level this high and continue to add bleach? I know I need it to pass the 3 tests, but do I do the overnight test the first night or does it usually take several days?

If the water is clear aside from what's on the walls, you need to keep it at Mustard shock for about 24 hours, regardless of the OCLT and the rest.