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I have used the BBB method for 2-3 years with great success. I have been out of town for awhile and neglected my pool and come back to a green cloudy mess. My PH is sky high..at least 8.2 by my test kit. I have a 27000 gallon vinyl. My question is how much acid to add to it to get down in the 7.5 -7.7 range?
Thanks
My other question is I have been adding a lot of bleach over the past few days with no luck in clearing the green. I'm guessing the PH level has to be correct for the bleach to do it's job? My total alkalinity is 140-150 range
Use The Pool Calculator to calculate an approximate dose. Going from 8.2 to 7.6 with a TA of 145 in 27,000 gallons says it takes 52 fluid ounces (6-1/2 cups) of full-strength Muriatic Acid (31.45% Hydrochloric Acid). The more accurate amount would be closer to 60 fluid ounces, but your pH measurement is approximate anyway.
Add the acid very slowly over a return flow with the pump running and after you've added it, lightly brush the side and bottom of the pool in that area to ensure thorough mixing.
Since you will probably be shocking the pool with chlorine to clear it, I'd lower the pH even more to around 7.2 which would take (according the The Pool Calculator) 112 fluid ounces of acid. The added chlorinating liquid or bleach will raise the pH when you add it so starting out with a lower pH helps out.
How much bleach are you adding, and what is your CYA level?
Janet
And, was your chlorine level high when you tested the pH? If it was higher than about 10ppm, it can give falsely high pH readings.