PH down

[mrjetson707]

I'm new here so I hope I'm posting in the right spot. My PH is 8 so I need to get some PH down. looking online I found this: Doheny's pH Minus, 30 lb Bucket.
It seems much cheaper than muratic acid and the description says dry acid. I read on the forums here that either works. Is it cheaper because I'll need twice as much to lower the PH? is this a good deal or should I just get muratic acid? any advice with links is greatly appreciated

 

[mknauss]

Dry acid is sodium bisulfate. When used, sulfates build up in your water. Sulfates corrode metals and degrade concrete/plaster.

We recommend you use muriatic acid.

 

[BenB]

Agreed. The answer to your specific question though is yes, it takes more dry acid (by weight) than muriatic acid to lower pH by the same amount. So you shouldn't be doing a $/lb comparison.

Looking at PoolMath, it looks like it's a 4:3 ratio of dry to liquid 31.45% MA. i.e. 33% more by weight dry is needed.