After having our pool replastered at the beginning of summer, I took over the pool maintenance from my husband and have had wonderful luck with the TFP method. I'm planning to add borates via the Borax & acid method after reading such positive discussions on this site. I did have one question - I always use PH Down instead of Muriatic acid mostly due to convenience. Normally on the site, and in the calculator they are presented as either/or but everything I've been reading on adding borax only says to use the muriatic acid. I'm sure there must be a reason but wanted to understand why before I go making trips to Home Depot or wherever to buy muriatic acid.