Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Every drilled tank is already something like that. With the proper plumbing any tank can be 'self cleaning' in the same way that one is. I do not see it working for a planted tank, though. The idea that waste falls through the substrate may be OK for a non-planted tank. Coarse gravel would do what the marbles are doing in that set up.
The larger floor of a real tank would need more of a 'system' for cleaning, though. Under gravel plates, for example. Stick the siphon down the up tubes, and clean under the plates. I did it that way when I was trying the reverse UGF concept.
Sure looks like copper outlet. I am not sure that it is in contact with the water all the time, though. Only the out flowing water during a water change.