Big bubbles from overflow

I'm in the process of setting up my 135 gal tank, I just finished all the plumbing last night and I am currently doing a test run with plain water to make sure everything is working as intended. So far so good except I am noticing about every 10 secs huge bubbles are coming from the overflow line and bubbling up in my sump to that point that water is splashing quite a bit when they hit the surface... Any idea why this might be happening or what I can do to prevent it?

 

BTW the overflow bulkhead and hose are both 1 1/2 ", the overflow is being fed by a 2 ft long pvc pipe with 4 holes drilled about 2 " from the top.

 

You need to make a gurgle buster for the return line in the sump. A couple of PVC fittings will do the trick. I can get you a pic if you need. Also, your overflow standpipe in the tank sounds like it is not optimal for bubble elimination.

Can you post a pic of the standpipes? To me that sounds like the culprit of most of the bubbles.

 

You're getting bubbles because air gets pulled down the plumbing along with the water. Put a vent on your drain. Basically bring the plumbing down to the sump. Then change to a T fitting. Have one pipe going straight down to the bottom of the sump. You want this pipe to be as long as possible to give the air a better chance of escaping. On the other end of the T add a vent pipe that goes up about a foot. To reduce noise drill a small hole on a cap and stick it on the end. For the best results use the largest pipe you can for the T and the two pipes. The larger the pipe the less flow per square inch and the bubbles will have an easier time escaping. Use a reducer fitting to change size from the plumbing that comes down from your overflow to the larger pipe in your stack setup.

 

Great explanation. That helped me as well. I'll be installing that tomorrow.

Mark

 

An addition to the above advice: Easiest solution is a pump with a higher flow rate.

My quiet one internal pump (about 1000 gph with a pretty low head) gurgled like crazy. My GenX PCX40 is a much louder pump, but doesn't gurgle at all (though I still get micro-bubbles in the drain).

The LFS guy confirmed it, he sets up large tanks and said that it's a common issue for folks that don't have quite enough jump in their pumps.

 

Here are pics of the pipe in the overflow along with a pic of the tubing going down in to the sump, these pics are with the return pump turned off. If you have a pic of a gurgle buster that would be great.

 

I could give that a shot. I thought I was done with the plumping...

 

I am currently running a little giant 4-MDQX-SC, I was told this is what was being used on the tank before I purchased it so I figure it would be enough. The overflow seems like it is just keeping up with the return when I have it on.

 

Mine was 'keeping up' but the overflow was only about 1/2 full. With the Gen-X running, the water level inside the overflow is only an inch or so below the inlets.

So despite the fact that my quiet one techinically 'kept up', any additional water I added simply raised the level of my sump rather than putting any additional height in my overflows. As a consequence the overflow was sucking in a bunch of air.

Once I put the GenX back on, the overflows filled back up and all was right with the world again. The stronger pump was moving water out of the sump fast enough to keep the level of the tank up. Once I put the weaker pump in, it couldn't get water out as fast. So while the tank would certainly equalize (it's not like my sump was overflowing), it was equalizing at a lower level.

I'm running 1 inch flexible tubing as my drain in a 130, so it seems like we have very similar setups. I could be wrong, maybe your setup just needs a gurgle buster, but I'd let you know what I've seen.