This 100%+1 tank too young
+1 fiddling with lights too much
I think that’s the main reason I’m having issues. I’m using 4 ai hydras and I put all the frags on the highest rock without light acclimation.If your water params are all good, I would suspect the lighting. (too much!)
I dang near killed all my monti's when I first started. I bought monti's thinking they were easy, and then struggled getting any of them to live, let alone grow. Realized my lighting was way too intense. Backed off the lighting and they all recovered and are now doing great.