Hey guys. Some reason my ph has been getting lower and lower in one of my tanks. It's just a 10g with a Texas Chiclid, Blue Crayfish and goldfish in it. My tap water is around 7.0 -7.2 right from the sink but I just tested my tank and its down to about 6.0 again. I've been trying 30%+ water changes every few days for a week and a half now, but its not helping. =\