If it were me I would use some powersand It is in the system for a reason. It helps to keep the lower portion of the soil from becoming anarobic. it is acctually a pumice stone base and not really so much a sand. at least thats how I see it. In my next build I am going to use Aqua soil personally. I have florite black, eco complete, and floramax that I have all used in the past and sufficeive to say I have been dissapointed. If I would have just coughed up the extra 10 bucks a bag I would have been happier.