Skimmer mod

[cindre2000]

I am trying to convert an old Berlin XL into a recirculating skimmer. I really hated this thing when it was set up stock since the bubble reducers make the actual reaction area really small. So I romoved all of the inner tubes and how I just have the main body. I am going to have the original inlet (at the base) be the new outlet drain, w/ standpipe. The original outlet drains (at the top) will be turned into feeds.

I have cut two holes in the body and I will be putting on a GenX 1000 needle wheel pump. I have two questions:

I originally planned to have the inlet of the pump face down and the outlet be parallel to the ground to minimize the time the bubbles are in a pipe. However, I feel that might trap air behind the magnet. Am I right or just overly worried?

Secondly, any ideas as to how to introduce the air. I did just have some 1/4" tubing going in the elbow before the pump; however, the amount that got sucked in was fairly small and the air tubing was fairly loud.

Thanx

 

[cindre2000]

So the skimmer is up and running; however, when the skimmer is all the way full, the pump no longer pulls in air. If I drop the hight of the water to about 2/3, there are lots of nice tiny bubbles.

Pump: GenX 1000 needle wheel, no venturi, just a 1/4" hose right up to the intake...

Any ideas why?

 

[ChrisRD]

Typically you need some sort of venturi or restriction on the intake side of the pump in an asperating setup to get it to pull enough air.

Any chance you can post a pic?

 

[cindre2000]

So, originally the skimmer was purely a venturi. I feel the design was terrible since they place tubes in the body to reduce the number of bubbles in the water leaving the skimmer; as a result there is at least half of the reaction area.

I removed those tubes, and drilled two holes, gluing in unions. I switched the flow pattern by having the water enter the skimmer through the top (the original exit) and flow out of the bottom (the original entrance). The bubbles are all introduced through the pump (GenX NeedleWheel 1000).

The intake is below the output, requiring an elbow. I drilled a hole in the elbow and ran R/O tubing (1/4 O.D.) right up the the actual impeller entrance. This sucks air fine in shallow water. However, once the water hight reaches a certain level, no more air gets pulled. That is my dilemma.

Right now I have an air pump hooked up to the skimmer, since it was overpowering the pump, I had to slice some holes in the line, at least until I get a gang valve.

No camera: just Paint!

 

[ChrisRD]

Considering how small the pump is and how low it is mounted it may be tough to get it to draw much air. More restriction on the (water) intake side of the pump may do the trick.

You could test the idea by removing the pump and submerging it in a similar depth of water and gradually increasing the restriction on the intake side (put your finger on the intake pipe) and see what happens...

If that works, an improved venturi/restriction design will probably do the trick for you. You can also try meshmodding the pump - it can really increase air draw over the standard needlewheel impeller.

 

[Nautilus1]

I think there may be too much head pressure on the pump. This is due to the height of the water in the skimmer. im afraid there is nothing u can do about this. U need a bigger pump or you can move the exit of the pump higher up on the skimmer body. You could cap of the holes u al;ready made and make some ne hoples higher up