I'd actually recommend doing a DIY sump/refugium for a reef, but anything is fine for FOWLR. The reason why I don't really recommend a wet/dry filter is that it's kind of an old way of filtering. The bioballs can cause an increase of nitrates over time if they aren't cleaned. I guess fostersmithaquatics.com has some good ones...don't really know which brand is best. I bought a 5 gallon bag of bioballs for a sump I was setting up and after finding out that there were better ways of filtration I sold the bioballs and went with the sump/refugium.