There is a diffrerence between zooplankton (animal) and phyto plankaton(algae). Micro is simply a broad indication of the size of the plankton.
Many corals with small polyps need "micro" plankton and not larger varieties. Typically , most corals will benefit from zooplankton.
Filter feeders and some others will use the phytoplankton which will also feed naturaly occuring zooplankton in your tank.
Micro zooplankton includes items such as : oyster eggs, prawn eggs, cyclopeese and so forth.
You can either add the DTs directly to your tank and let it blow around or dillute it with tank water and spray it a little upstream from the organisms you wish to feed.
The difference is DT's phyto are selected strains that are cultured ,it is micro plankton. Yes just add it to the water ,I would start with a small amount ,and guage thier reaction while monitoring nutrient levels.
I have used cyclopeeze in small amounts every day as part of my fish and tank feeding mix. I think it's a very good food. However, I think if memory serves me correctly that it is larger than other "micro plankton(such as oyster eggs) and may actually be too large for some sps. I will be trying out a product called coral frenszy which includes a number of micro zooplankton in freeze dried form.