i'm using a centrifugal pump to pump RO water.  The RO water originally has some fine air bubbles.  But they should leave over time.

I have a flooded suction with a 2.5" suction, and about 1ft of straight pipe before the suction.

I'm recircing the water right back into the tank, and it just continues to create bubbles and sometimes airy-foam.  The recirc back into the tank is under the liquid level and you can just see all the air bubbles discharging.

I dont have any leaks in the system, pump doesnt vortex or appear to suck air in any of the fittings before the inlet.  Any ideas?

1gibson, I tightened the bolts on the housing.  8 bolts.  eahc turned about 1/8th of a turn.  And the bubbles went away.

I guess i don't understand why it didn't leak under high pressure.  But it's fine now.

I spent all morning trying different combinations with the pump and the system to see if i could isolate where the air was coming from, finally decided it was the pump and tightened the bolts.. viola.Chemical pumps