Under sand pvc system??

[kayakrob]

I am getting a full tanks setup this weekend from a guy who has had it for 3 years. There is about 2" of live sand then a mesh seperator then about 3.5" of argonite based and other sand below. The guy said that he has a system under there that is a circuit of pvc pipes, they are circulating through with hoses and a powerhead (i think.) He said that when he installed it a few years ago it was all the talk on the forums, but it didnt make much of a difference when he had it in. Do any of you know what this system is?? If so, i hate the look of almost 6" of substrate but the system has been running flawlessley for 3 years and there is awesome water conditions, would i be able to remove this system to lower my substrate a bit. Also i heard that the mesh thing is a good ida so burrowing creatures dont go to deep. Anyone know anythign about this ? please help.

[B16A2NR]

It sounds kinda like a modified plenum. Ive seen a guy run it on a 125 where the pvc has small holes and he has the pvc draining out for water changes. I wouldn't think pumping water out of the pvc with a powerhead would be any good for the tank. Is there any mesh screening on the pvc?

[kayakrob]

There is a mesh screen between the layeres of sand and the pvc is in a very coarse sand, rice sized grains. There is not a lot of flow through the pvc, i think only enough so as not to build up waste in it. if it were just a regular plenum (thanks for the name of it) would it be a good idea to keep or does it realy matter? BTW it's a 70g with a footprint of 3x18 i think.