Bubbles in Closed Loop

[plutoniumJoe]

Everything has been going great for about 14months then almost over night I started noticing micro bubble in my tank. I initially that it was due to increased fan speed over tank(not). The bubbles seemed to be coming out of the closed loop. The loop is an OceansMotion 4way run off a Reeflo Dart. I checked all the pipes and there does not seem to be anyway for air to be getting into the loop.

The only other thing I can think of is that my inlets(3 X 2inch) are getting clogged by coralline algae. When I look at the dart it looks like there is a washer that occasionally travels the length of the shaft than settles back down towards the motor side.

Any ideas are appreciated.

Joe