I am in the process of putting together my 20H nano. My original plan was to put a 10g sump underneath in the stand. Well, it doesn't fit, but a 5 1/2 does. I know there are various DIY projects posted dealing with sumps but I wanted to know if anyone actually HAS a 5 1/2 sump witha 20 gallon nano. The tank's going to have an overflow box, so I think there will be enough volume to hold the extra water when power goes out. I'm just not sure if there is enough width to baffle the flow enough. Thanks for any advice!