micro bubbles

As the air is purged from the plumbing the bubbles should eventually stop. If not, it means the return plumbing is sucking air. This is usually caused by a tiny hole somewhere that is acting like a venturi. The water moving fast through the pipe creates lower pressure which actually sucks in air.

The easiest way to find the hole is to stop the flow with a valve or plug as you turn off the return pump. With water held in the pipes the little hole will start to drip/seep water. Look for the drip and tighten the joint.

If it's glued PVC, drain the water and wipe dry around the hole.  Goop some thick PVC cement over and for a half inch around the hole. It only takes a thin layer, but to ensure it holds, wait 15 minutes and repeat with another layer of PVC cement.

If it's threaded PVC and a little tightening doesn't do the job, unscrew the fittings and add a few more wraps of teflon tape.

If the threaded PVC joint cannot be unscrewed because of a glued joint up or down the line, simply cut the pipe somewhere in-between, unscrew the part and add the additional teflon tape to the threads. Screw it back together and then glue the two cut ends back together with a coupler. If it's a tight fit, remember that the coupler takes up some space so a half inch of pipe may have to be cut off to make it fit. In these situations I will usually put cement on all four mating surfaces, swiftly press both pipe ends into the coupler and give the coupler a 1/4 to 1/2 twist to ensure that the cement spreads and seals the mating surfaces. (In case you didn't know, this quick twist is how all PVC joints are supposed to be finalized to prevent a leak.)

I've found in these situations that Silicone is a waste as an external seal. Silicone does not stick to PVC nor to the black ABS material from which bulkheads are made. Neither does it stick to Vinyl Tubing so you can try tightening or replacing the clamp first. If that doesn't do it, check the barb fitting for imperfection that is allowing air and water to pass.

BTW, with an overflow setup, the only benefit from turning off the water flow to feed is that it stops floating food from going down the drain. I use a different method. I leave all pumps running. I rarely use crappy dry prepared foods and when i do, I stick it into the water with my fingers to keep it from floating. I thaw the best frozen food (Emerald Entree, Rods Food or a custom mix) and feed it a little at a time watching the fish as I feed, to be sure they eat most of the food before adding more. It's also a great time to examine each fish be sure it is fit and healthy.


Edited by Mark Peterson - March 15 2011 at 9:52am