Hi, MFK, I'm in the process of building a wet/dry filter for a 210 FW tank. Planning on using 2 sterilite drawer towers for dual overflows. What would make a good sump. The longer the better. dimensions under the tank are 18" by 84" and 38" high. Would like to have something about 6ft long, it would give plenty of room for refugium type of idea. I was thinking of going all out and making one of acrylic, but it seems too involved and pricey. Also a used tank (75-90 gal) I have been thinking about converting, but I haven't came across any with the dimensions I want. So any idea on what to use, such as Rubbermaid containers or anything else would be great!