Skimmer problem

hydroman · 11-30-2006, 09:20 PM

I built a Geoff skimmer awhile ago and it worked perfectly for the first month that it was set up. Yesterday I changed around the return plumbing and now it isn't functioning at all. The water flow is the same as before, but the bubbles flowing through the skimmer are all far too large (1/4" or larger). I have had a powerhead in the tank for awhile with a venturi and since yesterday, the size of the bubbles has increased immensely.

The skimmer is roughly 6' tall, 4" diameter with a 3/4" kent venturi run by a Gen-x Mak4. I maintain my salinity at 1.025.

I'm wondering if something was added to the water which has changed the surface tension. I'm pretty religious about washing my hands when I work in my tank so I don't think it came in on my hands but I could be wrong. Luckily I'm curing live rock right now so I don't have any corals to worry about.

Anyone have any thoughts as to what might have happened and a remedy?

Thanks.

Jeremy

Geoff · 12-01-2006, 12:37 AM

could you post a pic on how he skimmer is installed?

double check that you do not have debris in the venturi valve. check both the water and air inlets for the venturi valve. could you have put the valve in backwards?

G~

hydroman · 12-01-2006, 06:45 PM

The first thing I thought of was a blockage at the venturi so I checked both the air and water inlets however there was no blockage. Sorry about the poor picture quality, it's an old camera and a new one isn't in the budget. The first picture is the only one I could get of the whole skimmer and the second is the inlet (top) and outlet (bottom). All inlet plumbing is 3/4 inch and outlet is 1.5".

I just ran a test where I took some spa flex and ran it from the outlet of the venturi straight into the tank. It wasn't perfect because I had to use a 90 right after the venturi. If I allowed the air inlet of the venturi to run without restriction, the bubbles were extremely large. The only way I could get all or mostly microbubbles was if I restricted the air flow into the venturi.

sasquatch · 12-01-2006, 11:51 PM

if you need to restrict the air going in, your not supplying enough pressure, the pump is pretty restricted by all those 90;s, as the pump wears in its possibly lost a bit of head pressure, have a look at electrical conduit(grey pvc) they have a very nice radius

Geoff · 12-02-2006, 10:02 AM

sasquatch- Welcome to TRT!!! Love the Username!!!

just to expand on what sasquatch is saying. on skimmer the infeed pump should be as close to the skimmer as possible. the venturi should also be as close to the pump as possible. if it is not than like sasquatch said the back pressure on the downstream side of the pump would increase and limit the effectiveness of the venturi valve.

G~

hydroman · 12-02-2006, 12:36 PM

Welcome Sasquatch.

Originally, I had the venturi immediately after the pump but the pressure was too much for the venturi to handle. I ended up with my air line mostly full of water and no bubbles. That said, I think with some creative use of spaflex, I can eliminate one 90 on the upstream side of the venturi and two on the downstream side. It's worth a shot and PVC is cheap. Thanks. I'll let you know how it works.

Jeremy

hydroman · 12-02-2006, 09:18 PM

I replaced three 90's with spaflex and very wide radius turns however it hasn't made a difference. I'm still getting almost no small bubbles. I would understand if this problem had started when I first hooked up the skimmer but it worked flawlessly for the first couple of weeks.

I've torn apart the pump and cleaned the impeller and made sure it wasn't clogged and moving smoothly. Is it possible for a pressure rated pump to decrease in discharge as it ages, or gets ready to die. I picked up the pump used and it was already a few years old.

Any thoughts would be greatly appreciated.

sasquatch · 12-02-2006, 10:37 PM

Thanks Geoff!! always nice to be piped aboard lol.
Jeremy.. my beckett did this one time, what I found was a dead snail jammed in a valve and 2 pieces of clear plexi(dont ask cause I dont know) so maybe fish something thru the pipes? to check the pump try elevating the pump up to the display and right into the venturi. Any unusual noises from pump or excessive heat?? hmm remember that the pipe from the venturi to the skimmer will have to "pack up" with micro bubbles before the big ones go away. keep posting we can fix this lol

Geoff · 12-03-2006, 01:36 AM

do you have a pic of the setup before you updated it?

G~

hydroman · 12-03-2006, 10:28 AM

The first two pictures are of the original plumbing and the second set are of the new plumbing.

sasquatch · 12-03-2006, 11:02 AM

Hydroman, do you have the outflow from the skimmer under water or just pouring into the sump, when mine is u/w the flow is cut way back

hydroman · 12-03-2006, 11:23 AM

Right now the outflow is under water about a quarter inch. I've done it both ways and haven't noticed a difference because it is only about 180 gph through a 1.5" pipe.

sasquatch · 12-03-2006, 11:26 AM

Jeremy, its been running all night and no better?

hydroman · 12-03-2006, 11:55 AM

It's been running for at least three days with no change. When I first hooked up the pump to the skimmer and ran a test, I had approximately 180 gph. This morning, I duplicated the test and came up with 140 gph.

sasquatch · 12-03-2006, 12:07 PM

so logic reduces to blockage or pump degredation?