Tiny air bubbles from return line

[Snitter]

2 weeks ago i put in a sump. I used loc line for the return ends. I have no bubbles going into pump area. No leaks. Was wondering if the loc lines will draw air in or if i just dont have enough flow to get the bubbles out of the line? its a 700gph pump. i have 3/4" pipe going to one return and 1/2" to another end. I turned the 1/2" off for awhile that seemed to help but didnt solve the problem. I did lose a few gph as i had to close my intake valve down. Any thoughts Thanks

 

[luxauterna]

I have always wondered if loc line causes this as well. I've had multiple tanks before that I have ended up with microbubbles in the DT (with loc line returns) but I couldn't find any in the return section of my sump. I, however, have not had much micro bubble problems with straight hard plumbing from return pump to DT with pvc only. Any others have opinion?

 

[FishGuyTy]

I maintain and instal aquariums and we get called out a few times a year to fix people's tanks after a new pump or something was installed. Just this last week, one of our service clients had an external blueline 55 HD and when I got there to service the tank for its once a month visit, it was full of bubble. The ball valve between the sump and intake to the pump had failed and was sucking air and leaking slowly. Other instances have been caused by barbed fittings and people not using a smaller tubing diameter than the fitting. If too big of hosing is used, you can get air around the barbed fitting. All that being said, it sounds like you may have a problem with flow, or lack there of. Try keeping the loc line outlet submerged in the DT and unplugging the pump to back syphon any trapped air bubbles. Dont let the syphon suck any air or start the little "tornado" at the surface or you will have to start over.

 

[AZDesertRat]

You mention "intake valve"? Just what do you mean by that? Pumps should never have valves or restrictions on the suction side. If you need to throttle flows it should always be done with a ball or gate valve on the discharge side of the pump.

Can you describe your plumbing a little better or even better attach some photos?

 

[FishGuyTy]

The tank was installed by someone else. The ball valve was installed, I assume for stopping back siphoning during WC when the pump is off. I never used it and it was just there. There is no need for a ball valve on the system and it was replaced with a union.

 

[FishGuyTy]

Oops, thought that was to me. Agreed, no intake valve on pump inlets.

 

[AZDesertRat]

The question was intended for the OP.

 

[Snitter]

I have a bean animal overflow. That's where I had to close valve down so I wasn't sucking air. Sorry about not enough info. I have to suck air in return when I turn off pump cause I don't have a check valve installed. Its on my to do list. I will tighten clamp on barb fitting and close one return and leave it that way and see what happens. Thanks for the help