Rough/siphon type effect where water flows into sump

Haifisch762 · Nov 8, 2020

Has anyone encountered this before? First time doing an actual sump because this is a bigger tank than what I’ve had so far. It’s a 20 gallon sump for a 75 gallon tank. 3/4” return, and 1” coming from the overflow down into the sump. The stand pipe is the original owner’s (bought the setup used). Bulkheads and plumbing under the tank are all new.
I’ve read about using a PVC tee at the end to prevent this, but it’s made zero difference.

That’s what it looks like. Calms down if I cover the hole at the top of the stand pipe, but then the overflow empties and sounds like a toilet.

That’s the top of the stand pipe for what it’s worth. Any ideas would be appreciated.

Haifisch762 · Nov 8, 2020

Welp, thought I had a solution - I closed the line for the return partially (the pump isn't adjustable that I know of, so I used the valve that I installed under the tank) and it seemed to do the trick, but then I looked at the overflow and there was barely any water movement in there. I thought about trying the same principle to the shutoff on the other line (the one that fills the sump) but didn't want to risk backing anything up in the overflow. This thing is becoming a pain in the rear.

DCR · Nov 9, 2020

If that is your only overflow, that is going to be an on-going problem at high flows. I have not heard of any solution. It looks like you have a return line in the overflow. If so, I would look at converting that to a second (full siphon) overflow (Herbie), and have the return go over the top. The Herbie and Bean Animal set-ups are designed to eliminate this issue. You would only send a trickle of water through your current overflow and the full siphon take the bulk of the drain flow.

SteveMM62Reef · Nov 9, 2020

You are trapping air, due to the pipe being below the water line. My Recommendation is to put a “T” in your Sump, with as tall as you can fit extension, with a Cap on it, Drill progressively larger holes in the cap, till it quiets down. If you shorten the pipe so it’s above the water line, you may get excessive splashing, and salt creep. BTW you only need to glue the “T” on the side and bottom run, not the top.

Haifisch762 · Nov 9, 2020

DCR said:
If that is your only overflow, that is going to be an on-going problem at high flows. I have not heard of any solution. It looks like you have a return line in the overflow. If so, I would look at converting that to a second (full siphon) overflow (Herbie), and have the return go over the top. The Herbie and Bean Animal set-ups are designed to eliminate this issue. You would only send a trickle of water through your current overflow and the full siphon take the bulk of the drain flow.

Yes, the return is in the overflow. That's how it was set up before I bought the tank. I did look at the Bean Animal setup, but I'm hoping to avoid putting another hole in the tank.

SteveMM62Reef said:
You are trapping air, due to the pipe being below the water line. My Recommendation is to put a “T” in your Sump, with as tall as you can fit extension, with a Cap on it, Drill progressively larger holes in the cap, till it quiets down. If you shorten the pipe so it’s above the water line, you may get excessive splashing, and salt creep. BTW you only need to glue the “T” on the side and bottom run, not the top.

Let me know if I'm visualizing this correctly - So the pipe from the overflow comes down into the sump, there's a tee at the end of it, then on one side of the tee there's a 90 and a straight run going back up out of the water, with a cap at the end?