Tried to make the tank quiet but it is now louder

[worrballer]

So I tried to make my tank quieter. Just messing around with it really; the noise wasn't too bad.
Well, now it is. I thought I'd be able to drill a hole in the overflow pipe above the water line in my sump so the air would have a place to escape instead of making bubbles (and therefore noise) in the sump. But now water and air escape creating a constant spitting sound.
Is my logic wrong? Did i make the hole to small? Is it to close to the water line?
I really thought the hole in the pipe would act like a vent and the water would be able to flow freely into the sump and therefore make it quieter. Can someone help me out and show me where I went wrong?
Here is a pic of my overflow set up:

the left is the drain and it has two holes on the cap in the back to stop the "flushing action". Works fantastic I just wanted to make it a little quieter (it is right next to the couch and makes it difficult to watch a movie once the kids have gone to bed).

 

[worrballer]

Any suggestions?

 

[al&burke]

I would get rid of the elbows in the overflow box, just get a couple of strainers. On the tee on the outside of the tank put a cap on the top part of the tee, what I did was just drill a few 1/16" holes in the cap just a few at first then more if needed - or what I eventually want to do is put a small valve so I can control the amount of air going in. You should be fine once you get the right air behind the drain.

 

[dempseyjosh]

if the left is the drain, what is the right? i'm just wondering because i'm going to be building an overflow soon.

 

[al&burke]

The one on the right is a back up I believe, if the water was to get higher that the top of the elbow, for what ever reason this one would back it up. If the OP uses both for drains it will get much quieter for them.
JMO