I am starting a 30 long aquarium for a GSP. What subrate should I use? I have crushed coral in my 10 gallon which I was going to mix into the 30's substrate to help with the pH. The guy at my LFS sugested cichlid sand for the pH but it is very expensive. I like the look and the price of crushed coral but the guy said it would be too rough on their bellies. Any other sugestions that are on the more reasonable side or is the pure crushed coral good?