PH is only part of the equation. To get an accurate reading on how soft or hard your water is, you're going to have to test for GH, KH, and TDS. Also, unless you're breeding soft-water species or keeping rift lake cichlids, most fish available in the aquatic trade can deal with PH values from 6.0 to 8.0. What kills the fish most are rapidly swinging PH values. Keep the PH stable and you should be fine. I think the only time you should have to worry about PH and water hardness is if and when you decide to keep dwarf shrimp.
Last edited by Monster Fish; 10-04-2012 at 06:45 AM..