Micro Bubbles

[H@rry]

I just set up a three tank system with a common sump. I have an external pump. I used teflon tape on all the fittings. On the pressure side I had a couple of leaks that I corrected with RectorSeal pipe thread sealant. That stopped the leaks. Now I notice that the return spouts are spitting out a lot of micro bubbles. I don't think they're coming from the skimmer in the sump, I think I have a leaking fitting on the intake side of the pump between the sump and the pump. I don't want to have to take everything apart and dope the fittings again. Is there anything that I can paint on the threads to seal the leak?

Thanx
H@rry

 

[AZDesertRat]

How is the suction side of the pump plumbed? Starving the suction of a centrifugal pump can cause cavitation and microbubbles. Keep the suction as free of fittings and restrictions as possible. No bends or changes of direction is best, straight from the sump to the pump with maybe a ball valve and union on the pump side for maintenace and thats it, no elbows or elevation changes. The larger the pipe size the better usually a size or two larger than the discharge piping and no sponges or foam to cause restrictions. Centrifugals like what is called a flooded suction with positive suction head or in simple terms several inches of water above the pump so it does not have to try and lift the water which they are not designed to do.

One way to tell if its starving is to valve down the discharge side slightly and see if the situation improves, if bubbles decrease or go away its probably a starved pump.

 

[TritonsGarden]

Had that same problem. I put aquarium silicone around the joints and turned off the pump for a couple hours to let it dry. It's held so far.

Jack

 

[H@rry]

Thanx Jack. I'll go to Lowe's tomorrow. (I haven't been in three days, they probably figure I died!).

Now that I'm thinking about it, why would you want to turn the pump off? Seems like you'd want the suction to pull the silicone into the fitting. I kinda doubt that it would pull it all the way through. I've been looking at it for a week now and hoping it would quit by itself. If you tried to set up something that would let that small amount of air though it would probably stop up with dust or something.

 

[kfennell]

Well is it on the intake or the outlet side of the pump that you are siliconing, I think he means turn it off if youre fixing the oulet side since there will be positive pressure in the pipes.

 

[H@rry]

Turns out it was just too much flow through the sump. I got a flashlight and looked in the return section of the sump and there were bubbles everywhere. The baffles were doing no good. All the churning from the overflows was just flushing right through. I throttled back the returns and it improved greatly. It's also quieter now! That made M@ry Ruth a lot happier.