pond filter noise

Is the gurgle like a 'burp' i.e. bubble releasing or like a falls
within the pipe? I am trying to figure how the flow gets to sound like
a gurgle.

How big a diameter does the closet flange have? Our returns are 4"
toilet flanges exiting 55 gal barrels. They handle a large flow. The
water flows down a standing pipe if we use the bypass we built into the
falls. The sound is the water falling about 4' vertical inside a pipe.
It does not compete with the waterfall, but is a distinct sound.

Do you know what water motion is causing your sound?

Jim.
Cam wrote:
I have a submersible pump feeding an upflow filter. It makes an
annoying noise. The pump itself is silent and the sound of the water
flowing into the pond is pleasant. The problem is the sound of the
water flowing out of the filter. It makes a rushing/gurgling sound. The
water leaves the filter through a closet flange in the side of a
barrel. Can anyone offer a tip on how to silence it? It drowns out the
waterfall.

Cam

Phyllis and Jim wrote:

Is the gurgle like a 'burp' i.e. bubble releasing or like a falls
within the pipe? I am trying to figure how the flow gets to sound like
a gurgle.

I used to have a veggie filter (15 gallon aquarium) mounted above my 200
gallon aquarium, and had plenty of opportunity to watch this phenomenon.
If you have a really big pipe, so that there's always air space, but the
water can pass it by, you don't get gurgling. If you have a really small
pipe, or the outlet is always below water level, you won't have gurgling,
but have to worry about the possibility of overflow. Probably, if you can
keep the outlet pipe vertical (at least from an elbow exiting the filter)
you won't get the gurgling.

What happens is that, as the water level in the filter rises, air gets
caught in the outlet pipe. As the water level (and pressure) gets higher
and higher, the bubble gets pushed further into the pipe, until it escapes
out of either end (causing the gurgling), then water rushes out of the pipe
until the level in the filter is once again below the top of the outlet
pipe - and more air gets into the outlet.
--
derek