Auto Top Off - Hi everyone I am working on all the components of this upgrade and the next is ATO. On my FW planted tank I set up a float in the sump return area, I have a 15 gallon reservoir. It seems to be running fine - these dry winter days really take a toll on the evaporation. Have any of you used a mechanical float on your SW sumps. Also I would like to make a column like reservoir with an airstone in the bottom and a submersed LED to light up the bubbles, kinda like those lava lamps of the 60's. This would be seen from the living room.