Backpack skimmer mysteriously stops taking in air

[seppler]

I have a very simple backpack skimmer with a MJ-1200 running it. I have the standard "basket adapter" and venturi hose it comes with. The skimmer has been working great for months. Three days ago I removed the basket to clean it out. I do this about once a week. After I put it back on and turned the pump on I got no bubbles. I don't mean no skim, I mean NO air whatsoever being sucked into the hose/pump. Over the past three days I have tried the following (not in this order):

 

1. Switched to a new MJ-1200 pump.

2. Let it run for a few hours with the cap off the venturi hose

3. Let it run for a few hours with the cap slightly closed on the venturi hose

4. Let it run for a few hours with the cap completely closed on the venturi hose

5. Replaced the basket, hose and venturi cap.

6. Yelled at it.

 

None of the above worked! This is a ridiculously(or so I thought) simple device. I have taken a straw and blown into the venturi hose and I DO get bubbles into the skimmer, but they stop when I stop. So, If anyone can advise me in this I would greatly appreciate it.

 

Thanks,

 

Rob

[reefmontalvo]

Salt creep has blocked your intake hose at the point were the intake hose connects to the pump at the venturi. This is common with that type of setup.

[Brian Ward]

normally you would boil some RO water in the microwave and then stick the air intake hose in to draw in the hot water and break down the salt. i'm not sure how it's blocked, but I think you'll need to manually clean it or maybe replace the hose. if that's even the problem. you said you already cleaned it, so I'd probably double-check that everything is completely clean.

[zygote2k]

Might even be calcium build up. AquaMedic skimmers are famous for this.

[extreme_tooth_decay]

try replacing the intake hose?

[lanman]

You all realize how ticked off she's going to be when she cuts the blocked up 1" off the air hose, and it starts working...

 

bob

 

After re-reading - she replaced the venturi hose, and basket... I'm sure she must be talking about a psychlone (or whatever it's called) skimmer. I have one on my rock-cooking tank; and even though it needs constant adjusting - it's never stopped making bubbles completely...

 

Hmmm.....

Edited December 28, 2008 by lanman

[reefmontalvo]

Well after screaming at the poor skimmer, I'm sure she is pissed enough.

[seppler]

Hi,

 

Thanks for the help and comedy. Unfortunately, it is not so simply as salt in the tube. I have done some more tests with it, and still have not solved the problem. I have separated the pump from the back-pack and it creates bubbles just fine. This lead me remove the back pack and completely clean it out. This has not helped. So, now I have only two possibilities that occur to me:

 

1. There is an air leak of some kind where the pump feeds into the backpack letting air escape - I checked this with a "snoop" test and found no air leak

2. There is some sort of weird back pressure going on that either prevents the bubbles from getting into the backpack or absorbs them.

 

Neither of the above make much sense, but it is all I have got. So to summarize:

 

1. pump is fine

2. hose is clear.

3. Combination of pump, venturi, and feed hoses into back pack creates bubbles but NOT when hooked up to back pack.

 

- Rob (not Sharon)

[AndrewB]

Sometimes you'll get a problem if the water level in the skimmer is too high relative to the water level in the tank, especially with CPR BakPak skimmers. If you have any media in the skimmer, take it out and give it a try. Check the outflow too to make sure there's nothing slowing the water flow from the skimmer back to the tank.

[seppler]

Those are good suggestions, but I had already tried them. I would include photos but I can't seem to get the attachment feature to work. Any other suggestions?

 

Thanks,

 

-Rob

[kevinlo]

Hi Rob,

 

Is the venturi before or after the intake? It only works well if the venturi is before the intake. Here's what I did.

 

Take the stock venturi attachment for the maxijet. Cut down the nubs on one end of the venturi so that those nubs fit snugly in the pump intake. I glued mine in place with weld-on #16 but that's not absolutely necessary.

 

The next enhancement is to cut off half the width of the impeller blades and do a mesh mod. That will result in pulling much more air and finer bubbles.

 

If that's still not enough air, you can add wooden airstones.

 

A few mods make the backpack a very nice little skimmer.

 

Oh, and pulling the bio bale out of the second chamber and replacing it with chaeto and a clip on lamp seems to work as well. The chaeto grows very fast.

 

I'll try to post some pics of my setup.

 

Kevin