I have been planning to do a DIY Wet/Dry filter for some time. The only reservations I have are in coming up with an over flow. I've seen some complaints that these only skim the surface and therefore don't do a great job of mechanical filtration. Since I first thought of a making my own wet/dry filter (about a year), I have wondered why you couldn't just use pumps to suck the water out as well as back in (other than cost obviously). This would seem like a better way to do things, since as long as you use the same pumps both ways, you're flow will be the same; you wouldn't have to worry about over flow problems if the power goes out, and you could suck water out from different levels of the tank. I'm sure there must be some reason why this isn't commonly suggested, but I just haven't seen it. Can anyone answer?