Skimmer turbulence

[hydroman]

How much turbulence do people have at the top of their skimmer? I've been observing mine through the top and while I get some fine bubbles, it's looks like it is boiling which seems to me means that I'm getting lots of large large bubbles. The skimmer is 5' tall and 4" diameter. I'm using a 3/4" venturi powered by a gen-x pcx 40.


The venturi and skimmer inlet are at the top of the skimmer and the outlet is obscured at the bottom.

I just measured my discharge and I'm pushing approximately 160 gph through my skimmer. It works out to be 2.5x tank volume. I've looked at skimmers people are using and they have over 500 gph running through their skimmer with little to no turbulence. Since I'm getting turbulence and I only have 160 gph running through the skimmer, does that mean it's more an issue of bubble size? Would large bubbles increase turbulence? Maybe I can find a needle valve to put on the air inlet to my venturi.

Any thoughts or suggestions?

[Geoff]

that is plenty of pump for the valve. i fugured you would be getting a bit more out of that than 160gph. you should be getting closer to 400gph with that pump with that head pressure, even with the venturi.

what happens if you take the air inlet tube off?

what is that valve 3/4 of the way down the skimmer?

do you have chambers inside the skimmer or is just an simple tube with an inlet and outlet?

do you have that pump running full borre?

G~

[hydroman]

Yes, the pump is running wide open, although it is possible that there is a partial blockage in the line feeding the pump. It's not easy to check because I would have to drain half the sump so I don't do it very often.

The valve 3/4 of the way down was an old inlet for the skimmer but there was too much head pressure there for the venturi to work so I moved it up.

I don't have another chamber inside the skimmer, the inlet of the skimmer just points down.

I'll pull the tubing off the venturi this evening and see what that does.

[Geoff]

can you extend the inlet just a bit further down? even 6" would be good. just enough to keep the turbulence from the incoming stream from disrupting the foam being formed up near the neck.

that pump should be plenty powerfull for that venturi valve. surprised you are only getting that little flow out of the skimmer.

G~

[hydroman]

I've thought that moving the inlet might make a difference too. A while ago I installed an elbow and 8" long piece of pipe pointing down to the inlet (on the inside of the skimmer). It didn't make a significant difference.

It looks like tonight it going to be a testing night. As well as pulling the tubing off the venturi, I think I'll play with inlet lengths, and maybe hook up the 1/2" venturi again.

It's funny, I'm not half as frustrated with my skimmer now that the sun is shining...

[hydroman]

Last weekend I hooked up a wider diameter tube to the air inlet of the skimmer and I'm getting substantially more foam than before. So much so that it's actually creeping out of the vents in the skimmer cap. I'm still adjusting it but hopefully I can more skimmate out of it now.

[Geoff]

Originally Posted by Geoff

what happens if you take the air inlet tube off?

G~

this is what i wanted you to try. most of the time it is a restriction in the air flow to the venturi valve. go with as wide a tube as possible.

G~

[hydroman]

I tried it briefly and there didn't seem to be much of a difference between no tubing and the larger diameter tubing. I didn't run it very long without tubing because it sounds like a jet engine and the skimmer isn't in my basement.