Looking for some help/ suggestions on what i fear is likely STN... a few acros turning white from base heading upwards. Not new growth i don't think because there had been tissue there previously and these areas don't fluoresce in UV. Parameters are/ have been stable with alk around 8.3, calc around 420, mag about 1450, ph 8.1-8.3, Nitrate about 12 and phos around 0.08. Par is around 250 for where these are at. My max par at the moment is about 300. about 10hr light cycle that ramps up and peaks in middle and then ramps down. Neptune Skys so i hope diffusion is adequate enough.
I dose live phyto daily, and sporadically (not consistently) use Korallen-Zucht flatworm stop (haven't seen flatworms, just figure it's good to use) and some other KZ things like coral love. Last ICP test was last month with no issues other than low iodine which i dosed to to try and raise. Had been using microbacter 7 and waterglass often in order to combat dinos in combination with pods etc... so i did have another ugly stage a few weeks ago but neither of these frags were overrun by algae.
The one frag is my rainbow's army growout contest frag having some recession around base. The other is an aquatic man table that was doing find a few weeks ago, but i decided to move off the frag rack onto rockwork. I have another random tenuis that is doing same on a frag rack (but has reached higher up the frag).
Any suggestions for stopping/ reversing this? maybe move to lower light? Initially I thought maybe not enough light or maybe they were shading themselves out so I had moved the table more directly under the light to try to reduce shadowing (par move was very similar), but I'm not so sure after checking par and having other corals nearby perfectly happy and growing. I haven't wanted to mess with lighting or flow for fear of creating new problems, but I'm open to suggestions. Any thoughts on actions? Best just to leave it alone and hope for best?
Tank is only 9 months old so it is fairly young though I have some live rock and this may just be part of the game at this point... just sad to have some things thriving and some that appear to be heading south.
sorry for dirty glass - i think i may have won fight against dinos this past week but I haven't cleaned glass yet around frag racks.