I want to build a DIY sump but my fear is creating something that will inevitably overflow and flood my living room. Is it possible to design a sump that will not overflow ? I have a 40 gallon AIO tank but I want more space to have a refugium and a better spot for my protein skimmer. I've purchased a HOB syphon and a small return pump but I'm still trying to figure out the best design. I picked up a 20 gallon (standard) tank at PetCo's 50% off sale. I'm looking for any thoughts and suggestions.