Durso question

What would happen if the "breather" holes on the standpipe were drilled too large?

 

Possibly more audible noise than what you'd ideally want.

 

So that would be the worst case scenario?

 

will it increase the flow vs smaller holes?

 

That effect would be negligible. The flow rate is governed only by the pipe ID.

 

I see, thanks, just trying to track down a problem, pipe seems to be flowing less water lately, the tank level has risen a bit and I can't figure out why! Driving me nuts!

 

If my understanding of standpipes is correct, then the fastest you could possibly drain from the overflow would be with a full siphon in your standpipe. So no holes in the durso with that scenario. I believe the problem with that, though is the water will end up fluctuating up and down in your overflow since it's constantly playing catch-up. Your overflow should always be rated at a higher GPH than your return pump and as such, it will be draining faster than your pump can refill.

Introducing the hole in the top of the standpipe allows air to be sucked down the pipe with the draining water. This lowers the overall GPH down the pipe (In comparison to a full siphon) and helps to even out the drain but introduces the gurgling sound now that the air and water are mixing. A larger hole will allow more air into the pipe increasing the gurgling sounds but will not increase the flow down the pipe.

A good way to regulate the air entering the pipe is to drill a 1/4" hole at the top. Silicone a piece of airline inside of it and put an adjustable valve at the end. The more you open the valve the more air you let in. This lets you fine tune the drain and find a happy medium between flow and noise.

The above is just based on my experiences when I had an overflow setup on my tank.

 

Two things I'd check: Make sure the air hole isn't plugged up with salt creep. The hole does have to be big enough for it to work, and a pinhole won't cut it. Besides that, check to make sure there isn't something inside the pipe itself creating a restriction, like a snail or algae build up.

 

The smaller the hole the faster the water will drain. If the hole is too small it will pull all the water out of the OF chamber and the water will become noisy. You just need to play with the hole size to get the right flow. Add some electrical tape over the hole to get the flow right. I have seen other use silicone to close the hole up some.

 

any good ideas on how to clean the pipe out? Not sure what I can use to "snake" the pipe out