Hey iocod, i used a 20 long all glass tank as a sump for my 90 gallon. All i did was make a bubble baffle to stop the bubbles my euro reef skimmer released. All u need to do is figure out how much space u need for your skimmer then silicone in an over under over baffle system. Try to leave as much space on your return section as u can cause thats where your evaporation will occur. I dont know how high u need your water level in the skimmer but my optimal level for my skimmer was 6-8 inches so i decided on 7 inches and bought 3 pieces of 1/8" thick glass with polished edges at local glass shop for about 20 bux cut. First piece of glass is 7inches tall, 2nd is 9inches siliconed one inch off the bottom of the sump and the 3rd piece was 6.5" inches tall....all spaced 1 inch apart. Heres a pic to show u what i did...visuals always help me. If u have any questions feel free to ask
