losing all my birdsnest HELP!!!!

[jstew600]

this may be a long description, sorry.
i have a 250 display tank, 40 sump.60 gallon frag, 40 gallon sump.
the 250 has been up for almost 2 years and going well. a couple months ago my gatorade BN (about 4" across) started receding so i moved it to my frag system. it has been recovering well. about a month later my bird of paradise(about 4" across) started STN from the stem, i figured it was light deprived. i fragged it into 4 pieces and also moved to frag system. Also has been doing very well since. over the weekend i noticed my pink BN (about 8" across) branches turned white, but the monti cap had grown into it a month or so ago and figured it was just winning the battle. i cut the monti and BN back. next day half the BN ha RTN. i fragged what i could and moved to frag system. I also niticed that my ORA green BN (about 3" across) was not looking too hot.the next day half the frags of pink BN were dead and ORA (still in the 250 display) also bleached dead. 2 days later (today) i noticed one of the bird of paradise frags in the frag system is RTN. i have acros, digitata and monti in both systems that are doing great. last month i switch from Kent salt to Fritz RPM( one 20% WC done in each system since), and dosed Acropower one time in the last week (first dose of AP ever, was using Brightwell coral amino prior).
i need any advice i can get, this is driving me nutty!!!

250 gallon
Ca 460
ALK 8.4
PH 8.1
MAG 1600
SAL 1.026
temp 78.5
PO4 .015 Hanna ULR
Nitrate 1ppm
amm 0
nitrite 0
dosing EVS B ionic 2 part with pump
esv carbon and BRS GFO in reactor

60 gallon frag system
Ca 425
ALK 8.4
PH 8.1
MAG 1440
SAL 1.025
temp 78.
PO4 0.0 Hanna ULR
Nitrate 2ppm
amm 0
nitrite 0
dosing EVS B ionic 2 part with pump
esv carbon and BRS GFO in bags

 

[Piper27]

I have never had this happen with birdsnest but I heard people always have trouble with them when alk swings.

 

[jstew600]

Alk has been stable within .5 for the past 9 months at least.

 

[Alfrareef]

Alk has been stable within .5 for the past 9 months at least.

.5?? What unit?

 

[rovster]

I know people say birdsnest are "beginner" corals but they seem to be the most sensitive of all SPS in my experience!

 

[jstew600]

.5 dkh in my 250 display tank.

 

[jstew600]

i may have figured out my frag tank problem though. the numbers i posted are from sunday, i tested again last night and the frag tank is ALK 7.0, CAL 400.
i think from adding large pieces of monti and all the BN frags it put a hit on the system. but still not sure what caused all of this in the main display. it has been on going for a couple months now....

 

[Joey_bananas420]

If all your parameters have been stable and no change in flow or lighting. And being that it's a specific species of coral dying maybe it's a predator damaging them.