Gradual STN - looking for opinions

As the title says I'm dealing with what I fear is a gradual loss of my sps.
Started early July approximately 3 days after putting a phosban reactor online - as soon as I noticed it in 2 specimens I pulled it and it really hasn't been online since.  I also abrubtly switched from Vodka to the phosban @ the same time - I've since switched back to Vodka.
Since it started I switched to Instant Ocean (from Reef Crystals) and stopped all dosing (including limewater).  I changed 30g in 2 weeks (72g tank) and am planning on another 30g as I get enough RO/DI.
I don't know if it's the cause or coincidental.  I've read that phosban reactors can drop pH & nutrients quickly enough to cause bleaching or STN, but I would have thought it would stop after removing the reactor.
From what I've read on STN/RTN the theories are that it can be from various causes (params, parasites or disease) but there's never been a specific cause pinpointed nor a cure.
I also watched my TDS in my RO/DI (5 stage) rise from 3 to 24 to 44 to 55 in a very short period of time (3 weeks) so I assumed I have a damaged membrane that I've replaced this morning (had to order it).  What I don't know is what the dissolved solids are in the water and if they're toxic to SPS.
I have been battling nuisance algae since day one with this tank so I assume I have P04, I was also measuring N04 after stopping the Vodka.  I've read that Nitrates can both cause algae and kill SPS although I didn't think mine were that high (10).  I have been losing Astreas so N04 might be higher than I thought.


Zoas are fine along with LPS (frogspawn and candy cane), mushrooms, gsp and leathers.
Grape cap = okay but paleGreen cap - mostly bleachedRed cap - okay but pale
Ruffled Ridge - okay but paleGerman blue digi - looks deadOrange digi - okayBirsdnest - okayWar coral - top starting to bleach2 other favias - okayBlue chalice - lost 20%, then rebounded, then lost 80% in last 4 daysGreen stag - pale, possible dead Green pocillopora[/i] - seems okay, bleaching @ bottom but could be common from flow - several other specimens okayPurple mille - okay but color's offGreen mille - poor PE, 2 tips bleachingGreen slimer - poor PESuperman monti - 10-15% bleached one specimen, other 40% (same specimen/different location)Unknown sps - minimal PE, poor color
Here's where I need the opinion:
Should I heavily frag the tank or wait to see what happens?

• I don't have another tank to put my SPS in.
• I'm not 100% sure fragging will help - I fragged above the bleaching on my first two casualties and the frags perished as well.
• I don't know if there's a way to rule out a disease but I don't think it's likely as there haven't been additions.
• These aren't on plugs so I can't freshwater dip

Sounds like fun, huh?
-Eric

 

Alk stays around 8pH runs 8.1 - 8.3Temp 77 - 80
Not stable but not enough fluctuation to cause bleaching/death in every SPS.
I wouldn't be as concerned if I was having issues with a sensitive species, especially since I have softies and LPS - it's every SPS and started recently.
-Eric

 

With nuisance algae I certainly have phosphates & was changing from vodka to a phosphate reactor to combat P04 when this happened.
I wouldn't think elevated P04 would cause SPS to die unless it was extreme.
I've always thought my colors were on the pale side but I had good PE and growth.
-Eric

 

Hey Bill!
I checked for stray voltage right away and found 1.5volts - I thought that was high until I researched and found anything under 5 volts to be acceptable.
-Eric

 

The only other things I've done in the last 4 months was add LR and change carbon.

I started using a different carbon about the same time & took it off-line today to see if it's a factor.

-Eric