In-line pump making lots of fine bubbles

[Charles Ward]

Can anyone tell me what could be wrong with me in-line pump? It is a new customsealife T4 velocity and its causing all of the very fine bubbles in my display tank. The pump has 4 feet for horizontal travel and only 3 feet of head distance till it empties into the tank. The input and outouts are 1 inch but I placed bushings on them to accept 1/2 inch because thats what the return tubes are in my drilled overfow boxs. The pump does not make any noise and is level. Does anyone have any ideas what wrong? Thanks Charlie

[Coralfreak]

Most likely their is a leak on the output side of the pump, you wont notice any water coming out while its running as it will act like a venturi and pull air in.

[Charles Ward]

there is only a 1 inch vinyl tube fitted with a 1/2 inch barbes adapter with 1/2 inch vinyl tube that is connected to the 1/2 inch pvc return that in the overflow box. And all hose connections have screw hose clamps on them. I guess my question is how can I find that leak that is drawing in the air? Thanks for your reply.

[Coralfreak]

Turn the pump off, if that is the problem it should start leaking when the pump is off.

[AZDesertRat]

Your problem is the 1/2" on the suction side. You are starving the pump causing cavitation. You should have 1" at a minimum and better yet 1.5" on the suction side of the pump. Do you have a valve on the discharge side and have you tried restricting the flow on that side? Is the suction side completely free of any other restrictions like elbows, strainers or filters? If you are using a 1/2" barbed fitting the inside diameter is probably less than 3/8" if that and that will never feed a 1000 GPH pump.