"Dead" or live phytoplankton for large feather duster?

[Molar Mass]

I bought a hawaiian feather duster 2 months ago and it has gotten by so far without being fed phytoplankton. A week ago, some of the tips of the feathers looked bitten off, and then the entire crown fell off. Thinking the maroon clownfish had been attacking it, I moved it to another tank, and the feathers have since grown back.

While reading about crowns falling off, I found out that it isn't likely that a 35-40 gallon fowlr tank would provide enougth phytoplankton for a large feather duster to survive. There are about 10 dime-sized hitchhiker dusters on the LR, and the tank supports several bristleworms and rice-sized "shrimp" (copepods?). Still, the large feather duster, which has a 4 " tube (2" occupied) and had a 2" diameter fan, could be starving anyway.

I've been reading about different foods people feed feather dusters when their tanks can't provide enougth phytoplankton, and there seems to be two types of liquid food fed:

"Dead" phytoplankton -- Marine Snow (might have too big particles), Kent Marine Phytoplex

"Live" phytoplankton -- DT, Phyto Feast

"Dead" phytoplankton is much cheaper than live, but some claim it is messier and that feather dusters only eat live phytoplankton. I would be target feeding (pipette), so I don't think it would be that messy. I only have one duster and no corals, so I'm leaning toward the "dead" Kent Marine phytoplex since it has smaller particles than Marine Snow and it costs less.

Do large feather dusters have to eat live phytoplankton, or can they survive on dead solutions?

 

[Molar Mass]

I've decided to try the phytoplex, and I will report back with whether it works or not.

 

[Calappidae]

I never fed mine. They just sat there for months until my pistol shrimp decided to rip em up.

 

[Molar Mass]

The Kent Marine Phytoplex arrived, and so far it seems like it's working! It was $10 on amazon for 16 oz. According to the bottle, it doesn't have to be refrigerated, but I'm going to do that anyway to extend the usable life.

I took 1 mL and target-fed the feather duster under the base of the fan. It started moving a little, and the tips of the feathers curled a little. Eventually, a few pieces of what looked like poop came out, so perhaps this is a sign it was making room for food. I tried feeding some of the hitchhiker/micro fd's and they reacted similarly.
I don't know if it was actually eating or if it was reacting to preservatives, but I think it is a good sign that while it shrank slightly, it didn't hide completely.