DIY Spray Injector:

Here is how I built my spray injector for foam generation for my protein skimmer In my tests this generates more foam than a Kent Turbo 3/4" venturi.

The key to this is the nozzle design. I drilled 8 x 3/32" holes in a 1/2" MPT PVC plug. Here is a short clip of my nozzle.

Another one of the nozzle as I put it on and reassemble the injector housing. Note that I don't glue any part of the lower housing for convenient access.

Here is the injector housing looking down into the 1" inlet. You can see two of the 4 air holes I drilled. I probably didn't need this many. I would like to ave only 1 so I can add a silencer and so I can hook up a air flow meter to see what kind of air it's pulling.

After running for 3 months this nozzle is clean as a whistle. It did however clog once after I removed the prefilter on the MAG 5 I had running it. A small chromis got sucked in diced and did successfully clog all the nozzles. So always run with a prefilter or pump inlet guard of some type.