I'm very "old school" good lighting (solar tubes), constant water changes and spot feed with marine snow and mysis shrimp... but mostly just lighting and good water do the bulk of the work for me..
I don't feed my corals anything- I feed my fishes and corals MIGHT catch some scraps of fish food. Or they might not
JMO but IME more than enough "marine snow" occurs in a reef aquarium and I've never witnessed corals or anemones eat plant based matter (ie: phytoplankton or algae)
If I were to dose phytoplankton and/or marine snow it would go against the environmental conditions I'm trying to create in my aquarium.
I do believe a drip of planktonic matter that's animal based in origin would benefit my reef aquarium (ie: rotifers, etc. BRS 'Reef Chili' would be included here) and I had great results back when I used to feed my aquarium corals some baby clownfish foods.
IMO, it depends on the type of corals and the age/health of the reef tank. An aged reef has tons of planktonic and bacterial foods for corals, and additional supplements are not needed as much as a newer system.
Some LPS have big appetites and fair better with regular feeding. Corals like Acanthastrea in particular do better with feedings. I feed my Acan tank a nice mixture of plankton including live baby brine, live Rotifers, cyclopeeze, mysis shrimp, amminos and vitamins, as well as oyster feast. Just started experimenting with Fauna Marine products as well.