I skip phytoplankton in my Acro-centered tank, don't add it to the `mush' recipe I use.
Here's a good article on phyto, what feeds on it:
http://reefkeeping.com/issues/2002-10/eb/index.php
If you're feeding for the few corals that eat it, gorgonia or other animals ... by all means, please feed them
As for `feeding SPS' ... it's such a debated subject. In my experience, I can feed them/the tank very minimally - to fairly good results. But IMO when I feed more often [less amounts per feeding, more overall food added] is when my tank has grown/colored the nicest.
It's a delicate balance, as you need to be exporting all the unused food, waste, etc all right out - so feeding IME is partly based on how well your export is working.
But I prefer to feed more, feed beyond my fish. As for `what is best' ... I'm still figuring that out
I do like homemade fish food [shrimp/squid/shellfish/etc] which is hard not to have at least some pieces too small for fish [coral sized] nevermind I've often added small-food [cyclops-eeze, various micron-sized foods -particulate foods of various brands] to the mix.
It's really easy to `OD' on particulate foods and such stuff - more concentrated foods IME can be easy to overfeed - though with the BB, you'll see fairly quickly if you add too much. Generally, IME, less is more with such foods ... but I've found I liked my results better when feeding more, though the tank required me to be on top of all maintenance, skimmer cleaning, etc.
In my thinking, the real reef is `plankton rich and nutrient poor' ... so that's what I try for with my highly skimmed tank - feed regularly, fairly well, of various sizes/forms ... and export to keep dissolved nutrient levels within acceptable range.
Do realize, bacteria/detrital material can provide food to your coral as well ... so blasting off your rocks can be a small snack in a sense. Coral nutrition is a complex subject, but in my thinking - provided I don't provide a nutrient issue that impedes the coral, I'd rather give it as much energy-budget as I can to get the best growth/color I can.
However, it's taken me a long time to get to where I've got water quality under enough control to where I can see a difference ... though that's just my opinion.