Hello! I recently changed my substrate from gravel to the Black Diamond Blasting Sand and am now getting much lower pH readings than before. My pH out of the tap is 7.6, I keep crushed coral in the filter so the pH maintains at 7.6, 2 nights ago my pH tested at close to 6.0, I put in a fresh bag of crushed coral and now it is hovering around 6.8 I believe. 6.8 is fine for the species I have but I just wanted to know if anyone else had any knowledge on if the sand was making my pH fluctuate or if it may be something else. Thanks!