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Slow overflow drain to frag tank


smohr123

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Hi all,

 

I'm having an issue with slow flow into my frag tank. Hopefully the picture shows up clear enough. I'm draining one side of the display (durso setup) into the frag tank, with a shadow overflow from the frag back to the sump. I'm having slow flow from the durso so much, that the water level in that side of the overflow is the same level as my display. Even if I turn off the return pump, there's barely any flow to drain. I would think that gravity drain should be quicker than ~1gph. Yes, it's that slow. The other overflow (direct drain to sump) is working fine. My first step to remedy was to change the air line in case of any blockage, as it's been submerged in water for a while.

 

Any suggestions would be greatly appreciated. I thought about changing the setup again to have two return pumps in the sump, but I'm looking to avoid that if possible. Thanks!

tank setup.jpg

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Is the problem in the pink line in the center of your drawing? It sounds like there's air in the line somewhere. Is the Durso vented? Trying to interpret your drawing... Is there an elbow in the frag tank at the end of the Durso line? Any chance that you have a bubble there?

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Yes, sorry. The center pink overflow going to the frag tank (small tank on left) is the issue. Very basic drawing but elevations are pretty accurate.

The tanks been in this configuration for about 9 months, but this only started like 2 months ago.

Could be a bubble in the elbow. Should I have done 45s instead of 90? Any recommendations to remove the bubble?


Sent from my iPhone using Tapatalk

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If it's not glued, you could replace it with a tee. Then add an upright vent up higher than the Durso. You could also just drill a small hole at the top or the elbow.

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If the 2 overflows in the display are the same, you are going to have a hard time getting good flow to the frag tank. This is the same challenge that folks trying to repurpose 2 overflows into a beam animal setup have. Also, there isn’t much height difference between the overflow in the display to the “return” in the frag tank.

This is a tough one. If you get the flow you want to the frag tank, the other overflow isn’t going to get enough. I’m not sure I have a good answer short of raising the frag tank and simply pumping to it, and letting the drain of that flow through the display. Or making all the display overflow go through the frag tank.

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Height difference shouldn't make a difference with a Durso drain. It's not siphoning. However, narrowing of the drain from an entrapped bubble can be an issue.

 

@smohr123, another thing that I notice on your drawing is that the drain from the display to the frag tank has a U-bend in it. It's possible that something might inadvertently flow over the overflow and, at some point, get lodged in the low point leading to a clog. It could be grains of sediment or whatever.

 

You might be better served adding a pump to your sump (or a manifold) and driving the frag tank return separately. That would result in a more conventional solution.

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