Just finished getting up and running my 20 gallon refugium.
Return is 3 holes drilled into the acrylic, that gravity feeds back into the tank. I used egg crate to protect the drains from getting fowled by algaes. Also used egg crate for the top.
GPH is about 100.
I'm just trying a regular pendant plant light to see if the algae likes it.
Added pods i bought online, as well as 4 types of macro algae and a mat of sea grass. We'll see which one grows the best.
I also put in my horribly aggressive hitchhiker crab that came in on my Carribean live rock. Not sure what species he his, but man is he mean. He has about 50 small snails to keep him company.
Sand bed of 2 inches.