i check the pH in my tank regularly, and this has been happening for a while now. the pH coming out of my tap is a desireable level (7.0-7.5), but when i checked my tank last night, the pH was low again. I have crushed coral to bring it back up to correct levels. I have no drift wood to bring it down, only some ceramic ornaments & 2 fake plants. Could my water conditioner be brining the pH of my tank down? I use Stress Coat. What else could be causing my pH to drop down?