Generally, my answer to this question is "no," but...
Years ago, I used to feed the live "DT's Phyto" to my mixed 85G reef and never really saw any difference between when I started that regimen and before.
For the past couple of weeks now, I have actually started feeding some of the BRS "Reef Chili" on an every 3rd day basis. It contains some of the freeze dried phyto amongst other stuff. So far, my LPS corals seem to be happy and liking the little extra touch of food every few days. I mix it with ~1/2 cup tank water, shake the heck out of it for 2~3 minutes then slowly dump into a high flow area of the tank with the main return pump shut off. I let the powerheads circulate the mixture about for a good 15 minutes, then turn the main pump back on.
I use phyto feast from reef nutrition. I only feed phyto once a week. Zooplankton and high protein like oyster eggs are my favorite foods for coral. my clams seem to respond to it mostly.
I feed Inland Aquaculture I get at Reef Solutions. It's grown by someone fairly local to the Detroit area. Not sure if it's helping or hurting, but I've been putting a little in every day/ every other day. Doesn't seem to hurt anything... Also, it's slightly less expensive than I've seen DT selling for.
I just found out our LFS carries the DT's so I'm gonna have to go with that. Tried ordering Phyto Feast on-line twice from a seller on EBay. Both times it came in ****y warm, cheap shipping
Be careful. You need very little and you can pollute your tank quickly. Just watch your nitrates and adjust accordingly. I would start with a few drops every other day and build up.