Wavemaking return nozzles

[jroescher]

Looks just like these: http://www.hydor.it/inglese/flo.htm

They are pretty common. I've seen them on a lot of smaller tanks.

[caferacermike]

I had a hydor unit once. It locked up weekly. I had to constantly rinse it out. Finally about 2 months after buying it, it permanently locked up.

[LoneStar]

I think a penductor or eductor would work out better. It just depends on what size pump you will use them on.