I will chime in quickly as my debate is live on Fox!
B. What are your parameters? ( CA, ALK, PO4,Salinity, etc.)**** (I'll get accurate ones and repost)..............Yes please do as this can be a important factor on some of you other answers.
D. Filtration method (Skimmer, GFO, DSB, etc.)**** Tunze skimmer, 12x twist sterilizer.................. that twister is a UV filter? if so what positive you see in your tank from this?
G. What are you dosing? Dosing schedule?**** ca + mag monthly............... I do the monthly dosing but what is that based on? How much are you dosing and why monthly if you don't know how much you have to dose.
I. What brand of test kits are you employing?**** API's Saltmaster test kit.................. Please invest in better test kits if you want to go forwards, Salifert, Hanna, Redsea. or do a Triton total test.
J. What are you using for CA/ALK supplementation?**** No.................. you mention that you dose monthly but you have no supplementation....
K. What are you using for flow? (Pump names, how many, placement, etc.) Jebao WP40 x 1, WP25 X3. Placement midlevel, focused down on sps. One on far right, one on far left, one each on left and right back glass................... on what mode do you have it? As you know SPS doesn't like direct constant or close wave flow.
I think you have a balance problem on your hand.
Not knowing where your # are is not good.
I should get an answer from you if I ask you what was your PO4, ALK, CAL and Mag 2 months ago.
You need to register your testing # always as you can go back for what is changing when your tank was doing good.
Just follow up and frag that colony, check for pest and a dip isn't that bad as long as you use bayer as that is less stressful on a already stressed coral.