| 225 g with bottom drain? Cool.
Pond formula would give you a pump at 225 gph, right? For a small tank use double or more. I run my 90g goldfish pond inside with a 700gph, there is head loss through the dumb filter, and I run my 350 g tank with a 700 gph also (2 - 3 ft. head loss only). John, to be specific, you should look for a 500GPH.
Pond formula for the filters would be 50 - 100 g for open chambers gravity system (25 - 50%). Sounds just like 2 or 3, 30 G barrels, doesn't it? 30G barrels are 28 inches tall I think, so there is maybe a trick to using them on a 24" tall pond, but they are not hard to find for 5 or 10 or 15 bucks each.
The sticky part comes when you try to apply the formula for settlement chamber to the flow of your pump. Flow of 4 times the volume of the chamber you use for passive mechanical filtration (setttlement) means a 30G chamber can handle only 120GPH. This is why pads and things are used for active separation (straining) instead of passive separation, because it is hard to provide the large passive volume.
Mickey the windowman |