Hello everyone, I just want to let you all know that because I had problems with the PH of my water, I've decided to change my regular substrate to a crushed coral substrate. Although I've researched a lot about doing this, I couldn't find anything that would tell me not to do it. Also asked for advice on this site, about what to do with the unstable PH, which seem to have an effect on my fish and I was advised to buy crushed coral. The end result...The PH became so high that it killed my biological filter...my fish all died... I know those things happens, but I just want to let you all know of my experience, so then you will have a better chance than I did... The good news is that because my aquarium was already cycled, it only took me 10 days for it to come back to my normal 0.0 amonia and nitrite.