The fellow who owns his own, local pool store mentioned that sulfuric acid is a better way to affect pH than muriatic acid. I've not heard this before, and have always used muriatic acid. My SWG needed cleaning, and I used muriatic acid, which seem to work just fine. But he said sulfuric acid is better for pool use. Would love to hear from someone who knows more than I about this sort of thing. Thanks very much.