I have a 75gallon tank and I can’t get the ph to lower, when I do the test strip it comes back reading 9.0. Most of my fish are acclimated to it, but I tried to (slowly even) introduce two angelfish and one died, I’m thinking because the ph is so high. What can I do, no matter what I’ve tried the ph won’t go down. I’ve heard mixed things about adding distilled water to the tank, should I try that? The water is very hard.