If I were going to turn anything into a sump, it would be my current 10 gal. I want to reuse my current pc light which is a 40 watt x2 Current USA Orbit fixture. It seems to work fine at 16" depth (breeders) but at you get closer to 18" (talls) it really begins to peter out. The 20L will give me a couple more inches of front to back and several more inches of side to side. The refuse is planned to be behind a false wall on one side, kinda a two birds one stone, without buying a new light thing.