Micro buibles from my install of a used external return pump.

ddc0715 · Aug 14, 2020

I got a good deal on two little gaint pumps, and have finished the install. When I turn it on I was getting alotof micro bubbles. So I went back and inspected the plumbing. I found a few spots where with small drips. In the return line but none on the intake line. I have fixed those. And now I have no leaks. The micro bubble issue greatly improved but is still there. And its not a stead stream of bubbles. Its like a Morris code kinda acting. Bubbles then no bubbles, then bubbles etc. Kinda like a Flashing light. I here the churning of the air near the head of the pump area. SO can someone advise me on what to do next. So I'm kinda lost here. With no leaks where do I look or do I just wait it out.

dragon99 · Aug 14, 2020

Any pictures of the setup? Is there maybe a vortex forming at the intake that's occasionally pulling in air?

ddc0715 · Aug 14, 2020

I have to retake the pics. My s20 7 billion mega pjxels are to big for the upload. .

ddc0715 · Aug 14, 2020

Red is the return to diplay line and green in from sump line.

dragon99 · Aug 15, 2020

Impressive plumbing work. The impeller is maybe cavitating? Try slowing down the return flow and see if that stops the bubbles.

ddc0715 · Aug 19, 2020

ok here's an update. I have done the following to the plumbing.

1.reapplied PVC glue to all elbows and 45's on the inlet line
2. added tef tape all the unions. on both the inlet and return line
3. check for proper o ring placement with in the unions. on both on the inlet and return line.
4. tighten all thread union connects.
5. tighten down the pump head bolts (red). and applied silicone to the seal line (blue).refer too pic 1
6. applied silicone (not glue) to all the thread connects, both at the pump (yellow line)and at each end of each union (green lines)
7. applied silicone to the union faces themselves. I'm sure this was not needed but did it anyway. (green lines)
8. slowed the flow rate.
9. backfilled the plumbing by letting the overflows drain backward until all air is blown back into the return chamber. it never works the air always returns.
10. let water sit in the lines for a while in an effort to locate a drip. no luck. thinking about letting it set for several hours today. my tank should be fine right? i believe so.

this has helped but not removed them. the problem has gone from fast bursts of micros to a slower burst and fewer bubbles. I did see the biggest improvement when I readjusted the lower unit in the pic above then applied this regluing an silicone after that. there has been no improvement beyond the union adjustment. I'm pondering just cutting it or all the unions out and replacing it pipe. I see no need for unions anyway. ill just cut the pipes if I have to replace the pump in the future. also, to address or investigate cavitating im going to replace this 90 with two 45s? here's a video clip. these bubbles are making my tank look dirty with debris.