Alot of great suggestions here sounds like you may have a game plan which is ??
Your tank is still a baby not even a toddler like Wil
@Turkeysammich is implying and ever so true most babies don’t walk and talk at six months!
From the very very beginning your LFS who set up the tank was dosing LC most likely from the new rocks and sand which can take three to 12 months depending on the amount of build up inside the rocks plus water changes until they even out and stop leaching. Honestly I never add any rocks unless they’ve been soaking for at least six months or longer with water changes in between. I want to see that yellow snot ( sponge growth) and feel the slime coating before adding to DT..
So especially with the added bio load combined with not enough nutrient export ( water changes, Turf Scrubber, less feeding, refugium etc) you will never resolve your situation!! I wish there was a magic dosing potion!! That sulfur reactor sounds interesting never explored that before. Totally on board with ICP plus an aquabio dna test plus can confirm you beat ick with the latter test..Dilution is the Solution with more dilution water changes weekly with less feeding will be the immediate impact your looking for reducing numbers until you get a handle! Either reducing bio load or better export! Just keep it simple! Best of luck