Bubbles in Sump

[jjwilley718]

I have a 26x26 cube rimless tank. It has an external overflow with 1&1/2 in bulkheads. I have a very simple overflow, as its just a little bit of 1" pipe with 90s on it. I am running an Iwaki 20rt, which pushes 492 gph. I am getting lots of bubbles in my sump. The good thing is that they aren't returning to my tank at all, but what can I do to alleviate the bubbles.

 

[Ty Hamatake]

I get a lot of bubbles pushing through my sump when the overflow is draining significantly faster than the return is... returning. If you have the ability to, try restricting your overflow drain (I'd suggest a gate valve. I have a ball valve and kick myself every time I have to adjust it). You'll want to make very small adjustments at a time with a good bit of time in between each adjustment to let things stabilize.

 

[Engloid]

I wouldn't put any valve in it unless you have a second line that's for emergency use.

The reason I say this is that if you have only one drain with a valve, and something gets in it, you may overflow your tank.