You may want to check this site regarding nuisance algae and eggcrate in this type of setup:
http://www.worldofseahorses.com/nursery%20setups.htm
A deep sand bed seems to be the consensus now for the base.
I would agree with Serk on the gutter. Cut the top out of a 1/2" piece of PVC just wide enough for the filter outlet. Glue it to the outlet then elbow the pvc into the tanks.