correct size pump????

The noise is from the bulkhead or the overflow? Or course if you increase the pump size you're going to increase the flow rate and potentially increase then noise

 

Have any pics of your drain?  Is there an internal overflow box or just upturned PVC with some sort of screen?

I'm getting ready to do an overflow through the back of the tank (as opposed to the bottom) and have been researching ways to keep it quiet.

Many people suggest a "Calfo" style overflow, search for it.

Take a look at these links as well that discuss an external riser on the back of the bulkhead (via a "t") will an air hole drilled in the top similar to a Durso.

http://archive.reefcentral.com/foru...id=4286205
http://www.reefcentral.com/forums/s...d=11926792
http://www.google.com/custom?q=nois...l.com&sa=2
~Eric

 

Chris, how does the water go from the overflow into the bulk head? Is there anything attached to the bulkhead going into the tank? This peice is called a standpipe. There are different designs, some are louder than others. One of the quitest is a durso standpipe. The give and take is usually the amount of flow versus noise.
I would be happy to help with this if you want to post a picture or drawing of what you have. I am sure others will help as well. 1-1/5 inches should be able to handle 850 GPH without a problem.

 

Posted By snowman82 on 01/19/2009 03:19 AM
Its an upturned pipe with a PVC screen, I'll submit pictures this afternoon to help show what it looks like. When i looked at the tank when mike had it it was really quiet and he ahd a 650 pump. now that i have it and i got an 850 on it. its really loud haha, maybe its just the acoustics of my house It's not the acoustics of your house
If you look at the links I posted and do some searching, you'll find that it's a common issue with this type of overflow/bulkead in the back of the tank.
I'm getting ready to do the same thing and am concerned with the noise as well!
Is it a gurgling?  Rushing water?  Or toilet flushing sound?
Most likely the water is creating a siphon that needs to be broken - there are several ways, but a regular Durso most likely won't work as you don't have a standard internal overflow box within which to place the pipe.
The idea is to add a siphon release to the drain, easiest way is to add a vertical pipe from a "T" on the back of the bulkhead, put a cap on this pipe and drill a small hoe to adjust flow.  Start with a small hole and go larger until the noise is gone, like a Durso setup.  This outside pipe is similar to what's on the roof of your building to allow the plumbing (sinks/toilets/washer/etc.) to drain freely without creating a siphon.
Here's a pic:

This one looks like they did a quick fix without a cap, but gives you a visual idea of the vertical pipe and "T":

~Eric

 

This is another style that is more elaborate:

And discussed here:
http://www.reefcentral.com/forums/s...t+overflow
~Eric

 

What he said . /DesktopModules/ActiveForums/themes/_default/emoticons/biggrin.gif
You have your answer. Its just like the plumbing in your house, you have to vent it.

 

Are you able to rotate the pipe with the screen? Yaybe you could try putting it sideways or playing with it a little bit...otherwise like everyone else said, you need to vent it with a durso or something similar.

I also think it would be more beneficial to have 2 separate outputs into the sump rather than combining both overflows into 1 output.