Undergravel Filter

[amosf]

With HOB and canisters you have the same or greater loss of flow. Read the fineprint on their tech specs. You will see something along the lines of ideal installation, no media or restrictions in place. SO if you remove all cartridges, pads, media, floss, and any restictions with ideal head placement...you get this. Now, add your floss, media, cartridges, pads and let them filter out crud. 50% at best and decreasing over time.

Yep. With mine I tend to set them up as wanted, then measure to see what real flow I get. That way I can also check flow later and see whether it has dropped and by how much due to blockage, whatever. I find 50% is an okay figure to work with when buying. Only some give all details about pump flow, ideal flow, actual water filtered, etc...

 

[Squawkbert]

I, too think that there is still a place for the UGF, provided it is made correctly. Best ones tend to be hand made from 1" PVC, manually drilled, covered w/ plastic screen. All you have to do is buy elbows, tees, pipe, (a clear one for lift tubes), plastic screen and have a drill, hack saw & soldering iron.

Is you want sand, put 1-2" coarse gravel down on the filter, then add sand. I used to do FO marine tanks like that - 1-2" cc or dolomite followed by 2-3" coral sand. Add some studly PHs and you've got it. Tanks set up like this recover their looks after a good vacuuming faster than anything else. Also - vacuuming can be made more efficient if you stir the sand manually, then come back when the lighter junk has settled - you get a higher % of it that way.