Thanks for the replies, much appreciated.
I realize it seems a little silly to blame a change in salts, to a certain extent I'm grasping for ideas.
In all my tanks over the last decade or two, I've only ever used Instant Ocean.... just thought I'd try Red Sea as I liked the idea of mixing and adding in the tank within two hours, where it seemed to take longer for the IO salt to mix.
The least accurate additive would be Kalk in the ATO is it's addition can depend on water amount of water evaporations. I add 1 teaspoon of Kalk powder per gallon. Via dosing pumps I add 17ml each component of ESV 2-part.
I noticed things start to go south about 8 weeks ago. First the bali slimer started to lose polyps and other colonies started to have algae growing on them. Colonies which were previously growing furiously
My Alk would bounce between 7.5 - 8.2 and once in a blue moon, say I ran out of 2 part, it could go as low was 5.8, but the corals were fine.
The first week of August I went on vacation and forgot to add kalk powerder to the ATO and I apparently ran out of two part fed by dosing pumps. The Alk dropped to 5.6, and today it's back at 8 dkh. What did happen is more torches melted, the acro's were already exiting the tank. I'm thinking the alk swing did the torches in, as well as a frogspawn coral.
The last time I lost a torch I believe it was due to an alk swing.
Which brings me back to the salt. As I noticed the acro's degrading I did more regular water changes (weekly instead of monthly 5G changes). I'm wondering if it perhaps is just a bad batch ? Or perhaps something got in the tank. My alk didn't change much going from Reef Crystals to Red Sea.
I don't test for phosphates although run periodically Rowaphos in a filter bag (if hair algae outbreak) I don't feed much, and the last time I checked they were zero. Current reading from the Hanna Nitrate HR is Zero.
The acans, candy cane, mushrooms and plating corals are doing fine. Just the Acro's and Torches took a nose drive. It's taken about 8 weeks for the Acro's to die, torches in 2 days (when I got home from vacation). The pocilliopora are doing ok. I've a green colony that is bleaching although it's baby colonies are growing fine.
Going forward, I'm going back to IO Reef Crystals tomorrow but will first send off a ICP test. Once received I'll report back the values. Should be interesting. I'm also going to dose Kalk via a pump throughout the day, more so in the evening to level out the pH which swings from 7.8 to 8.2... starts to drop at 10pm when the lights are out ( 250W MH, x2 RB XHO)
Cheers.