"Like crypt was alluding to, you want at least 1# of LR per gallon. Also, in regard to sand, there are a couple good threads in reef section about the amount. I have a 4" deep sand bed(DSB) to assist with the filtration process. What I have read here (I've only had the DSB) is that you want to be over 4" or less than 2". If it is over 2" but less than 4", the sand becomes a waste trap. If it is over 4", it can cycle the waste. I'm not 100% on if that is true or not, but it does seem to make some sense. " As I stated, I AM NOT SURE. There have been numerous threads along this vein. I am not married to the idea. I was putting it out there, as more experienced aquarists gave the info. I don't know either way.