I use two different style of diffusers.

One is the typical round airstone(2), and the other a cylinder(tube style)rubber membrane(1).

These diffusers are probably on the cheap end of quality, so....

I've had these diffusers in different configurations around the pond, and at different depths, and from that what I've thought is the stones seem to work better.

They seem to have finer bubbles and more boil than the rubber memberane tube jobbie I have.

Is this unusual? Are the pancake style rubber membranes different? Is it a low quality issue I'm observing?

Seems most quality diffusers I read about are the flat(pancake) membrane type. Are the tube style membranes a joke?

Do you know the slit size that is in your membrane diffuser?

Esshup, I don't have any spec's on my membrane diffuser.

I did have it out yesterday and cleaned it off some. After looking at the slits I would guess them to be ~3/16".

3/16 seems big to me.. But I'm definitely not an expert. I know smaller is somewhat better. And being a machinist 1/1000 of an inch is big to me.

Naw, that is just way too easy.

Yep. Not even worth saying anything!

Bahahahaha........ Now taking foot out of mouth, so my other foot can take it's place..

JD,

Looks can be deceiving...Just because there appears to be more roiling action on the surface with one diffuser over the other, it does not mean that it is necessarily moving more water. If there appears to be water being lifted in a "dome" above the surface of the water, this would indicate course bubbles. All airstones that I know of are course bubble. Most "tube style" as you describe them are fine bubble. While the surface aesthetic of a course bubble diffuser may appear to be moving more water, they actually move less water than a fine bubble diffuser. When we see this "doming" affect with our fine bubble diffusers, we know that there has been damage to either the diffuser itself or the fitting that receives the feeder tubing.

Ok, thanks Richard. That may be what I'm observing.

How are the tube style usually situated in the pond?

Previously I just let it sit on the bottom(and in the mud)

I read about an idea with a milk crate. I had a plastic one, so I put a brick in it, zip tied the unfed end of the diffuser(the very end past the membrane)to the top of the crate, zip tied the feed hose to the top on the other end(diffuser wouldn't reach all the way across), and carefully lowered it so it sat flat on the bottom.

It is horizontal. Is that correct?

JD,

Tube style is usually situated horizontally. I've seen some creative innovations where the tubes are twisted all around in a concentric twisting type configuration. Most tube style diffusers still need to be propped off the bottom because they have orifices all the way around the tube. You don't want to blow air down into the sediment. I think your milk crate idea will work.