Gurgle, Gurgle, Flush - Problems with my overflow

[Joyride]

If you're following my thread over in the member tank discussion, you'll know that I'm frustrated with the amount of noise I'm getting from my hang on back overflow.

I've spent the better part of the last month trying to come up with a solution, and thought I'd found it over on the Durso Standpipe site, where he showed a modification that used a Durso standpipe with an external overflow.

I disassembled things last night and took this photo of my version of this mod:


I drilled a hole in the side of the overflow and where you see my hand is where the T fitting would normally go. I've got about two inches of pipe going up, with a piece of hard tubing glued into a cap. Going down is about 24" of pipe that goes into a 45 degree fitting into flex tube into my sump.

The problem I've been having is getting the airflow hole just right. If there's too little airflow, it cycles quickly between siphon and flush, very loudly. If there's too much airflow, the pipe drains more slowly. The extreme end of that is to remove the top cap, which causes the flow rate to be extra slow and for the water to overflow the top of the tank.

I've been trying to come up with the perfect airflow hole and haven't been able to get it dialed in just right. What ends up happening is the drain works well for a while, then about every five minutes, I get the flush sound. Doesn't sound too bad, other than when it happens during dinner (the tank is in the dining room).

On the Durso site, he says that if you're getting the flush, it's usually because of back pressure in the drain line, not air hole size. However, in my case, there's virtually no possibility for back pressure since there's only one 90 degree fitting and a smooth curve into the sump. The connection into the sump terminates above the water level, so that's not contributing to back pressure either. Troubleshooting link here, check the first item.

The only thing I've gotten to work fairly reliably is to reduce the flow on my pump. (Side note: without the drain pipe installed, the overflow can handle way more capacity than the pump I'm using). This isn't a very good long term solution as I want to have as much circulation through my tank as possible.

Over at Premium Aquatics, I found a Stockman Aqua-Silencer made for overflows. The two comments say good things and the price is not that bad. I'm curious if anyone's tried using one of these. My plan would be to plug up the side hole and go back to using the bottom hole on the overflow.

Besides the noise, my other problem is that the water level in the tank is too high for my liking. It's constantly right at the top, to the point that you can sit on the floor and look up into the water to see the black plastic of the top border just barely submerged. I think the cause of that is the height I drilled my hole for the side opening. The Premium Aquatics overflow thingie looks good here since I'm guessing that it sits a little lower.

I'm open to any suggestions on these problems. I've been pulling my hair out trying to figure it out. Of course, I should have bit the bullet and just drilled the tank when it was empty. I can't imagine I'm the only one with this issue. I can imagine that others aren't as retentive as I am about extraneous noise, but I don't think I'm totally overboard here.

Thanks,
-Chris


Links:
my member tank thread: Joyride's first reef

Durso FAQ: External Overflow

Aqua Silencer: Stockman Aqua-Silencer Overflow Model: Premium Aquatics

[JustDavidP]

I've done lots o' things to try and "tweak" durso pipes. One that I found to work real well is drilling the hole large enough to insert some flexible airline tubing. Attached to the end of the tubing, is a plastic airline valve, like this:



You can then adjust in tiny increments to see what works.

Dave

[JustDavidP]

That silencer looks suspiciously like what I made :O

[Joyride]

Thanks David. I did try using an airline valve and even with the center pin entirely removed, it still wasn't allowing enough air.

I've done a ton of reading on this last night and tonight and actually found DIY plans and discussions on Steadman's site as well as a long thread started by Steadman on ReefCentral.

So, today I went out to the local hardware stores and picked up the parts to build one of these things. After I got home tonight, I was doing some more reading and came across some discussion in the ReefCentral thread that having a little bit of back pressure is actually a good thing. My setup had almost none. In the thread, Steadman talks that the inbound sump line should be as low as possible and submerged under the water, with a T connector at the end.

So, I got into my growing PVC parts bin and got the necessary stuff together, and extended the inbound line into the sump as deep as possible, with a T at the end. Pretty much cleared up the gurgle, gurgle, flush.

Of course, the water level is still higher than I'd like, so I'll probably still build a Steadman's so I can adjust the height some to change the height of the water.

The only problem is that now my skimmer is too loud. I think I'll save that problem for another night.

Have a good one!
-Chris

[JustDavidP]

earplugs

D

[CarmieJo]

Decide that you love the sound of gurgling water.

[NaClFinatic]

I am using astock AGA durso in my overflow. I had to drill extra holes in it to get it to stop the siphoning. That id make it much louder. It probably is quiter since I made a cover for my overflow, but mostly I think I got used to lots of water noise.