Overflow is driving me crazy

[Grandreef 2]

My overflow box is not working properly. When I first started my tank is was working nice and smooth until I put my hand in the water to place liverock, it then started to girgle! I bought this overflow( that is suppose to go at 600GPH) on ebay that looks like thishttp://www.melevsreef.com/prime_overflow.html.
I have a 20 gallon sump with a viaqua return pump 2300 and a Coralife 65 skimmer directly next to my input(return pump for skimmer is under fliter sock)
Those adapters that you can put on the overflow wont work with my system, they are to big, I tried to stick tubing to block thre air in my return pump. My output for my overflow bow is above the water line (does that matter). Should I put a control valve on my return pump beause when I just tried it the water level would always slightly drop. This is so frustrating and confusing. PLEASE HELP ME:fur:furious:ious:

[cpittmx]

I have the same type of set up and was having the same issues. It seemed that the depth of the box and angle were pretty sensitive to whether there was noise or not. What I ended up doing was taking a piece of air tubing that was about 5 feet in lenth and started snaking it down the standpipe until the noise disappeared. every now and then I need to move it a little in or out to readjust and get rid of noise again...but its a simple fix. I have a glass top and just leave excess tubing laying on the glass lid.

[jdallred]

http://home.everestkc.net/jrobertson57268/HGB/

[2slo4me]

+1 check the angles and if its still loud get a sponge in there that might work

[Grandreef 2]

Do you meen that my overflow box is angeled wrong? Would that Hofer Gurgle Buster fit, how big should I make the holes so 600 GPH can go through? I dont like the idea of always having to adjust the tubing are there any pther ideas.