Is It Sceintifically Possible To Suck In Air From The Output Of Your Return Pump?

Reef Maniac · 02-03-2002, 10:33 PM

I have a submersed Return Pump (mag2400) There are no air bubbles in the sump where the pump is. (I am positive the air is not being sucked in).
Is It Sceintifically Possible To Suck In Air From The Output Lines Of Your Return Pump? Like from a union fitting, etc... Wouldn't that force water out? Or would it act like a venturi?

Littlefoot · 02-03-2002, 10:41 PM

I don't think it is posible, you may have some air pockets in your output plumbing that on occation break free and give a display of air bubbles, but they should all go away after a bit unless you suck in some air.

reefcam · 02-04-2002, 01:07 AM

Yes. Helped a friend fix his air bubble problem that was coming from a fitting in the output direction area.

Depending on how the fitting was arrange, it can create a venturi effect. Hard to believe. I was too confused by this, but after changing out his unions, hose clamps, and making sure all fittings are tight, the problem we away.

He had an external pump.

gregt · 02-04-2002, 05:40 AM

Is the pump casing completely submerged?

It could be sucking air from the gap in the casing, if it's exposed to the air at all.

Another thing I've seen a lot with submerged pumps is that a vortex is created that sucks air into the pump intake that's as much as 4 or 5 inches below the surface of the water.

kestrel · 02-04-2002, 07:33 AM

If you are getting bubbles, another possibility would be cavitation of the pump. Basicly, the pump is ripping holes in the water that it is trying to pump. This could be caused by a restriction on the suction side of the pump. A good indication of this would be a lot of noise from the pump.

Daryl

EMAT · 02-04-2002, 08:24 AM

I have an aqua clear power head completely submerged and every 3 minutes it blasts out small cloud of tiny air bubbles. This pump is for circulation only, no hoses nothing. It's been doing this for years. I have turned it upside down, shaken it under water, I've tried everything to get any trapped air pockets out and it still does it. Maybe my Tang is farting underneath it.

reefguy · 02-04-2002, 09:46 AM

yes, the venturi effect can be applied on the discharge of a pump. you don't really want bubbles going through the pump impeller as they can cause damage to the impeller over time, although that usually occurs when there is not enough net positive suction head. anyway, if you look at it, many powerheads (hagen comes to mind) come with an attachment that utilizes the venturi effect to aerate a tank

hope this helps