Feeding
Heterotrophic feed availability is what limits corals in our tanks given all other factors in good standing
check your feed against known coral production threads
We all tend to be hands off, usually fearing tank upset, and feed only the amounts the current work load translates into X no3 or po4 reading. Perhaps that is still too less feed, easy way to tell.
You listed most other factors in good standing so don't concern on them, pick the one thing that is not A+, an exceptional feeding plan. Exceptional feeding plans and export will grow coral. current feeding description sounds common, not A+
A clue was that you didn't mention increased work done and sustained the last three months, water change work, to keep your current params in place but allow for much more spot feeding. Your corals are in neutral nitrogen balance, growth is neutral.
Cup feeding is an option where you cap off some frags on the sand or on a rock ledge with a creative cup/weight arrangement so that the feed you'd normally add to the tank goes into the cup first and that coral eats like a king for a day comparatively
Each feeding round is moved to a different coral. Creative capture or dwell time can feed corals better, not just adding more food overall and spiking nutrients. See if the foods you are using can be found as the sole feeds on other coral growth threads. Waiting on your tank to feed the corals is a choice, also a choice is to do your own feeding and change your wait times, you've already stocked this tank it's hungry and waiting and wanting feed.
if you'll get physically busier with your tank and sustain it three months while feeding much better you'll get growth. You do the work, not buy more gear to take up waste but real water change work to get that tanks metabolism upped. If it works then buy the gear to lessen your work
The fact your corals haven't receded is a statement to your tanks ability to grow good coral when you feed A+
My corals grow with less quality params than yours, solely because my feeding is tops. My tank is so small I grossly over feed it 50x too much and then do three back to back water changes 100% to export all the uneaten massive food. Corals have to be chipped out with dremel and vinegar off the tank walls, problematic growth. Feeding is the trick and the export work to allow it.
