Durso air surges

[dutch27]

I've been searching around and haven't found much, so thought I'd ask...

I recently set up a AGA tank with dual overflows and the typical pre-made adjustable height Dursos. With ball valves and creative plumbing I've mostly reduced the noise down to just the sound of the pump and skimmer. But, when I open the ball valves on the drains all the way, one of them gets random surges of air and is extremely loud.

My theory is that my return is undersized (500 gph vs two 1" drains) and I'm not putting enough water into the drains vs air being pulled in. I plan on upgrading my pump to something closer to 900-1000 gph soon.

Any thoughts on the surges of air and any possible noise reductions? As it is now there is still a pretty decent amount of sound from the water falling down the pipe in the overflow. I've had two tanks with dursos and overflows before and never this much noise. The only difference is that in both of those I had more flow from my return pumps, 500-600gph return for single 1" drains so return flow more closely matched drain capacity.

 

[scarface70706]

i use to have this problem but i fixed it by lowering the turnover rate. i think if you add additional flow it might get louder.

 

[OneReef]

The air hole in the top of the durso may need to be drilled bigger. To reduce noise, I stick some airline tubing in the hole to quieten it down.

 

[geo11]

I had the same problem. I too solved it by lowering the return flow, drilling out the holes at the top of the duso, sticking in about 6" of 1/2 in airline tubing with ball valves on them so I could actually adjust the airflow

 

[dutch27]

I tried some air line tubing this morning, and it didn't make any difference. I would find it hard to believe that 500 gph through two 1" drains is too much flow though (120g AGA for reference).

Granted my pump and skimmer probably make more noise than the water at this point, but the way the sound travels it sounds like the water noise is coming from a different room making me occasionally think my washing machine or sink plumbing has broken open, lol.

 

[moondoggy4]

Does the height of the water in the overflow box goes up and down.

 

[Playa-1]

I would suggest that you look into drain pipe venting options.

 

[geo11]

If you've drilled out the nipple on the top of the durso....try slowly covering it with your finger to reduce airflow....if that works then its the combination of air water thats causing the problem, and the ball valve will definitely help...mine's an AGA 210 so I'm sure its pretty similar