Anybody built one? Not a lot of sites still working that talk about
them, in fact I only found two, this one is pretty old:
http://tinyurl.com/24egq
I like this idea because it has a removable lid, making it easier to
clean if it were needed. One question that arises about this drawing
is why have a waste dump and a bottom drain? Couldn't one simply use
the bottom drain to flush the filter beads and dump waste?

The Larry Lunsford DIY bead filter has the advantage of being shorter
and a bit easier to hide in my situation, but seems a more difficult
to clean since it is on the side instead of resting on the bottom of
the barrel.
http://pw1.netcom.com/~larry_l/diy_bead.htm

I'm not familiar with these, but Ingrid says they have been known to
go anaerobic. I suppose that means they begin to produce hydrogen
sulfide, or other nasty stuff. I don't doubt this has been a problem
and I think any filter could if proper water circulation was denied
the aerobic bacteria. I wonder about the complex designs of some
beads and think perhaps the simple bead would work better with less
water flow, unless churned inside the barrel or subjected to greater
water flow or turbulence from air, like the Nexus filter uses.

I'm considering building one and place it between my present filter
barrels and the plant pond, which I need to rework in the next couple
years, before it falls apart. Anyone with experience could be helpful
and ideas are welcome.

Regards,

Hal