Our 3 experimental reef tanks comparing tanks using different substrates are already showing some significant differences. Since the tanks are set up the same and have approximately the same water chemistry parameters, which are close to those of natural seawater, these differences are surprising. Especially since they are being seen after the tanks have only been set up for approximately 2 months. These differences are the amount of encrusting algae that is occurring in the tanks using the Fiji and Caribsea substrates. This algae is actually becoming problematic and is starting to stress the corals. In an attempt to reduce this problem and to see the differences in the mud long term an additional 7 snails were introduced to all tanks. Unfortunately in these two tanks even these additional snails are having difficulty controlling the algae.