I'll start off with parameters. Calc 440, dkh stead around 8.1, 1650 mag. I don't dose mag, it's usually about 1500 but a few months back i had raised it with kent tech m to kill bryopsis. temp steady between 78.3-78.5. 80g total and i do a 10g water change every other week. I run GFO and Carbon, i don't test for phosphates or nitrates but i feed a decent amount and i have no algae issues in the tank, other than some minor bubble algae. I dose about 50ml of both alk and calc a day. What i have that is in the tank and growing are: ora borealis, monti caps, strawberry shortcake, blue sunset milli, ora hawkins, unknown purple acro, re planet, hydnophora, green stag, orange digi, ora ice tort, another unknown acro, possibly a tabling acro, and a setosa. there are a few lps as well. Now about a month or so back i ordered two corals, a ice fire echinata and a blue vermiculata. They did fine until the end of the second week, and then they started losing skin, within another two weeks they were gone. The place gave me credit for the lost frags, i did the same order, added a red dragon. Red dragon is still doing great, i'm running into the issues again with the other two. This time around after they started to decline, i fragged them up a bit, did dips on them accept for one frag of each, too early to tell what they are going to do. I just can't figure out why they are declining, and everything else in the tank is thriving. I also can't keep a birds nest in the tank. Not sure if those two things are related. Anyone else have any issues like this? Why would certain specific coral, in this case it looks like blue coral, not due well in my system. I have a reef breeders photon 48 if that info is needed, max at 76% blue 36% white.