return blowing bubbles

[dolphinman213]

on my small 20 gal setup, my return is returning nothing but fine misting of bubbles into dt-- i have changed all tubing, switched out three different pumps(all dialed down to handle the overflow ), but still bubbles in my tank, most of my fish are covered in micro bubbles. what is causing this and how do i stop it---there are no bubbles in the return area in the sump---what gives?

[James77]

Are there any glued PVC joints anywhere in the return line? What kind of tubing do you use?

Is it an internal or external pump, if so, what size is the inlet tube? I ask because the pump could be cavitating if the inlet is restricted too much. IDK if you would generally have a problem with cavitation on an internal pump though.

[Baka Saru]

Hey I actually have the exact same problem in my 90G, so im tagging along. I hope someone can find a reasonable solution.

[psteeleb]

there is not enought information for a specific answer but 3 things you could look for:

In order of most likely cause:
1) do you have weirs in your sump to de bubble your skimmer outlet? If not consider adding some or use a filter sock.

2) is the pump suction constrained in any way (as suggested), for example, small line size, long run of piping, valves, elbows etc. or a strainer

3) a small air leak at the return point - if the line size is reduced or restricted at the reurn point a venturi effect can happen sucking in air. Normally water would jet out of a leak in the piping, but if there is an in line restriction a higher velocity area may exists that can create a vacuum effect on the pipe joints (this is how the flow accelerators, eductors and car carborators work) - e.g. locline.

[DevilBoy]

I have also seen locline cause this. make sure your locline is securely locked and not sucking air from anywhere.

[Baka Saru]

Well I just turned off the protein skimmer and all the bubbles dissapeared and it runs and looks perfect. So what does that mean? Is the PS bad or is there a way I can adjust something on the PS so that the bubbles dont return with the PS on?

[James77]

What kind of skimmer? Do you have bubble trapping baffles in the sump? You could add a foam sponge at some point downline to trap the bubbles/

[Baka Saru]

Its an older Sealife Systems PS. I dont really see anywhere to put a foam sponge

[psteeleb]

Originally Posted by Baka Saru

Well I just turned off the protein skimmer and all the bubbles dissapeared and it runs and looks perfect. So what does that mean? Is the PS bad or is there a way I can adjust something on the PS so that the bubbles dont return with the PS on?

your PS is probably fine, they are supose to create micro bubbles to function properly. The issue is how do you get rid of them before returning the micro bubble infested water to the tank.

one way is using a filter sock or sponge, another is a bubble trap made of weirs that force the water to flow up and down before the water gets to the return pump. The up/down flow helps force the bubbles to surface and pop

if you don't have room for weirs you can also make a bubble trap out of a couple pieces of pipe

[PHILYD1]

You need to check all your fittings on the from sump to return pump, when return pump is running if you have a leaking fitting you wont no cause it will be sucking air in, i had this problem it turned out i shut pump down for about 20 min and saw one of fittings leaking just a little bit. i sealed it and all bubbles gone

[Baka Saru]

After messing with it for the majority of the day, I fixed it. The PS return was going back into the sump right by the main pump and it was about 4 inches about the water line and I guess it was causing bubbles that was being sucked up by the main pump. Soooo I put a piece of 50 micron foam sheet for the return flow to land on and that was pretty much the main problem. I also fine tuned the vacuum line that went to the PS pump. But hopefully this will help the others in this thread.