[Rcpilot]

I almost built my reef with a plenum and piping for controlled plenum wasting (CPW). I just couldn't find enough info about it to make me want to risk it. If I'd felt comfortable with it and had read success stories of CPW being used over very long periods, I would have done it in a heartbeat.

Essentially, you build an elevated sandbed over the top of a piping system. The piping system has holes drilled all over in it. It has screen wrapped around the pipes to prevent clogging. You either drill the tank down low on the side-- or have a tank custom made with a hole in the bottom--or pipe it up the back of the tank and then back down. Install a valve lower than the bottom of the tank.

You "waste" or purge the plenum on a set schedule. Weekly or monthly or whatever. You'd have to experiment to find out what frequency would work best for your tank.

The idea is NOT to pull oxygenated water down through your DSB. That would crash it almost instantly. The idea is to open the valve and create a sudden and massive suction that will pull out "liquor" from the lowest part of the plenum. The articles I read, the guy was pulling off a quart about once a week. I think it was about 300g tank, if my memory is correct.

Supposedly, the benefit of this, is that your DSB never turns into a garbage can that never gets emptied. You just slowly purge and pull all the waste right through it and "waste" the liquor out the bottom.

The idea sounded good to me, but it also sounded like you could really mess up if you pulled too much through the bed and introduced oxygen to the lower layers.

I run a refugium on my 30g tank. It's a CPR HOB w/skimmer built in. Capacity is 4.6g-which I think is quite a lot for a 30g tank. I think this fuge would easily handle a 55g or 75g tank. My DSB is about 4.5--5" deep. I love it. Does just exactly what I wanted it to do. Grows pods. Grows cheatomorpha. Filters out nitrates and phosphates. I have about 2lbs of rock rubble in my refugium.