Help with DIY venturi pump

[Foogoo]

I got a hold of a pond pump and I'm trying to add a venturi to it for use on a DIY euroreef type skimmer. The impeller has already been modded w/ half a bioball.

I've never seen a Sedra work in person, but this is what I've done so far:

The problem is it creates a few and large bubbles. Is it something in my venturi design? Or is the pump just not powerful enough?

Thanks.

 

[xtrstangx]

How many GPH is the pump rated for?

 

[Foogoo]

400 GPH

An identical venturi system is what powers the Rios and MJ's, so I'm curious as to why it's not working with this pump.

 

[jstraka1]

If you tested it in fresh water, then the bubbles will be big and few.

 

[Andrew]

Did you cut the end that's inside the pipe at an angle? Here's one I made.

http://www.freewebs.com/a3areefer/diyventuri.htm