I was feeding Phyto for most of 2018 with Feed Me Algae products. I didn't notice any growth increase but I believe some of the colors were maybe a little better on certain corals.
I haven't fed any this year at all but the growth really took off. Even during my neglect the last four months, actually things grew the fastest in that time. I went from changing 30% of the water per month to maybe 10% over the entire four months. (That's not 10%/month, that's about 150 gallons in 4 months vs the 450 I would have normally done in that time) Other than feeding the fish and stirring things up occasionally I only dosed trace, Kalk and made sure the CARX was running right. Some of the corals grew more in that time than in the previous entire full year. Hell, I only tested Alk twice since April and nothing else. I figured if the corals started telling me something I'd test. The only things they said were that they were quite happy.
I have about 80% of all my coral moved out of the system already. Last night Glenn and I pulled a good bit out and I marveled at the size some of the pieces hard grown to. I hope to have the system completely shut down this weekend.
In the end, I'd say feeding Phyto will not hurt anything and probably does more good than not feeding it. But stability is still KING.
I haven't used filter socks in a couple years, I wouldn't feed Phyto if you're using them. I'd also recommend anyone with a mature system and a good nutrient management system in place to try not using any mechanical filtration for a while and see how the system reacts. Stir things up a couple times a week by blowing the rocks off and blasting the detritus in the sump into suspension. I think you'll find that you've got plenty of coral food already there. When I say nutrient management above I mean a healthy thriving Chaeto refugium or ATS in place.
One last note to what I've been doing different this year is that I've been adding Brightwell's Coral Amino to the frozen food I feed. So the system got a little twice a day. I had been adding larger amounts at a time once or twice a week after lights out. After seeing that putting it in the fish food is how WWC does it I decided to try too.
Every system is different and the results are the sum of a crazy amount of differing variables from one to another. But I'd say that the coral Amino's, lack of consistent water changes with trace added every other day is what got my display thriving. Oh, I also have a ton of pods, they're everywhere. I even see them in my CARX and ATS. They are doing just fine with no Phyto.
I can't wait to apply this knowledge on the new system I'm setting up.