Here's all that has thrived for me under my 18w cf and atenic biocube.
Any paly, my favia is twice the size from a year ago and my candy cane once was 1 now has 4 heads and let me not forget my lil 3 headed blasto, so I'd also say pretty much any LPS. They don't need a lot of light nor flow. Most shrooms would work too, as well as rics.
On my 3G fuge I have a 24w cf, got palys growing already and the tank isn't even cycled yet-hitchhikers