River tank manifold problem

[jlorenzo]

I just recently finished my river tank manifold which can be seen here.
http://www.aquaticcommunity.com/aquariu ... hp?t=59017
I followed the same idea on the loach website except for I have one powerhead and no tube going down the middle, just a rectangular frame of 1/2 pvc. the powerhead is a marineland 1140 that pumps 300gph. At first it pumped great but now its seems to have weekend and the airation (which can be controlled by a valve on the intake hose) is now spotty and come in little weak bursts. At first it was a solid stream of bubbles and the current was much stronger. Now it seems to only works correctly when I do water changes and the water level is lower. Is there something wrong with the pump or do I need another pipeline going down the middle of the tank? Any ideas would be appreciated.

[JonasBygdemo]

Try cleaning the filters. If it doesn't work, you'll probably have to take out the powerhead and run it in a bucket or something to see that it's pumping like it should.

[Martin Thoene]

Check my comments here regarding R/T manilfolds with only peripheral tubing design:

http://forums.loaches.com/viewtopic.php?t=20031

Your filter sponge or the powerhead's intake strainer might be blocked. As regards the air you'll probably find that you need to provide a pressurisede air feed to the powerhead venturi from a small air pump when being used low in the tank.

Martin.

[jlorenzo]

it was the filter. I used sand as my substrate and when I cleaned the filter it looked like the dust from the sand when it was settling. I havent cleaned it since setting up the tank but that fixed all my problems. I use one of these filters.
http://www.amazon.com/Hagen-Fluval-Edge ... 02LL32RY/2