My sump started off as a 40 Gallon Breeder. I put a wet/dry filter in it with all the media removed. This allows me to place my reactors and my protein skimmer inside the tank. It also gives me plenty of overflow room for when the main pump is turned off. This picture shows it while I was test fitting all the equipment. I ended up not using the CA reactor in the photo. I broke it while trying to modify it. It was already cracked around the base and something got bumped that shattered the main chamber.
I ended up moving quite a bit of the equipment around inside the sump. All of the equipment fits in it, so I don’t have to worry about something leaking. It will just leak back into the sump. I glued the wet/dry filter into the bottom of the tank and sealed the edges so water can’t seep through. Then I added a bulkhead to break off the main return chamber. I ended up taking the bulkhead out. It was causing micro bubbles to enter the tank.
Here you can get a pretty decent view of where all the equipment is going into the sump. The Protein Skimmer will feed back into the main area of the wet/dry filter. The CA Reactor and two media reactors both fit into the main part of the sump. The heaters will go across the bottom of the wet/dry filter.
I spent a lot of time trying to figure out how to store water for the auto-top off. After looking at a lot of different options, I ended up just going with the standard 10 gallon aquarium. It fit perfectly in the side of the stand. I hadn’t actually planned on putting anything there, but it looks like it was planned all along. I’ll add an acrylic lid to it so that water won’t evaporate out too fast.