How big should your sump be?
Also to know is, how do I calculate my sump size?
1 feet cube area (1′ length 1′ width 1′ height) will preserve equal to 28 ltrs of water. Therefore, multiply the sump cubic area with 28 to find out the water storage capacity of sump/tank in liters. Above formula is applicable if your tank appear as rectangle or square in shape.
Just so, how big should my aquarium sump be?
What Should Be The Size of Your Sump. At a minimum, your sump should be 20% of your tank. If you have a 75 gallon tank, then your sump should be at least 15 gallon. But in reality, you should go for the biggest size that fits in your stand (remember, more water volume, more space for media, etc).
You may find due to the 90 gallon size (usually 18-18.5" wide tank) of your cabinet your choices are limited. I put a RS-200 Eshopps sump under mine. It's a basic sump with two filter socks. Very quiet, just the slightest trickling sound of water flowing through the socks.