Not necessary but I do it to keep my feather dusters happy. Phytoplankton is naturally consumed by Zooplankton (e.g. copepods). If you don't care about copepods (and maybe only care about the big amphipods) - then it's not necessary to dose. Fatheree (author for tridacnid clams) would also posit that phyto is not a MUST for clams -though clams will eat.bmwalley said:Hey I was wondering do I have to dose with DTs planton if I have a mature refugium running??