Lots goes on with Acro's...
They want good quality water... low nitrates & phosphates.
They want intense light
They like higher flow
Your water quality is now getting better for you, so you are doing what you can there.
As I remember from your earlier post, you have dual 175 MH on your system. These will work, for Acro's placed higher in your tank, and mostly directly under the lights.
I don't know, or remember, what type flow you have in your tank. If you have power heads or Seio's helping what ever flow through your sump? Acro's tend to like the higher flow rate, not directly on them, yet a good flow of moving water around them.
This also leads back to your original question here... about Feeding. Acro's, for the most part, are Detritus eaters. What that means is, the BEST food you can give them, is what your fish in your system waist! Having a good flow, helps keep this fish waist moving around the water column, feeding your corals.
SPS's don't (again, generally) do anything with stuff like Phytoplankton... so I keep away from that.
For me, I make my own food for my fish. I purchase the frozen Shrimp, Scallops, Squid... toss that in my blender, add some of the jared oysters, toss in a few sheets of Nori, add some Selcon and RO/DI water. Blend, then pour into freezer ziplocks. Place this mush in the freezer laying flat on a box, so the mush is about 1/4" thick, and when its feeding time, I break off a chunk and thaw in RO/DI, then feed to my tank. Gives me a little of everything, without the preservitives some prepaired foods give. Not to mention it being much more cost effective also.