Need some help with a venturi skimmer

[Icefire]

I have a won CU-125 skimmer w/ mj 1200. The stock pump is supposed to be 500gph.

I did a clean up on it and the venturi is restricting the flow way to much. So I drilled the venturi 1/4" and enlarged the air hole a bit.

Now the skimmer almost overflow with the exit valve wide open and there is a vortex in it. If I hook up an air pump, I get big bubbles but a dense colum. With the air pump it will overflow.

Any idea?

 

[Icefire]

bump

The foam is removed and the pump is connected directly to the venturi (U tube removed)

 

[Icefire]

I just tryed a needle point canvas mod (mesh) with a 3/4" pvc endcap with 3x 1/4" hole for water flow and 1/4" for air.

I removed the stock venturi, still getting a vortex and high water level.

If I remove the 2 90*/valve on the output pipe, water level drop about 2".

The vortex is created by a cylinder inside that sucks water to the output+swirl of water flow by the pump.

I guess I could mod the output pipe larger in PVC but I still have the inner cylinder to remove.