When to lower PH

[tnt69]

My PH has slowly been creeping up & this morning is at 8.0. Should I add some muriatic acid today (& how much for a 30,000 gl pool) or wait till it is alittle higher?

[aylad]

I would go ahead and lower it now. Do you have a SWCG, or something in the pool that aerates the water (spa, waterfall, fountain, etc.) If so, creeping pH is something that you probably will always have to deal with. Regarding how much, I don't know how high your TA is, so you could start with a cup of MA poured very slowly into the return stream, careful not to splash on you, the pool, your eyes, or breathing fumes...give it an hour or so to circulate and then test again to see if your pH moved. If so, then you have an idea of how much more to add to stay in a 7.2-7.8 range. If it didn't move, then add another cup, retest in an hour, etc. until it starts moving downward. (The pool calculator indicates around 15 oz to drop it from 8.0 to 7.4, but that' assuming a TA of 40. If yours is very high, it might take a lot more than that but I have no way to know, so I'd rather stay on the safe side and recommend a cup at a time.)