what could be the cause..
 

hello all, just got some acans and they are all pretty much trashed now! when i got them they looked pretty good.
alk is about 7 - 7.25
salinity 1.024
calcium 400
ph 8
nitrate 5 ppm
ammonia 0 ppm

the only other thing i can think of is they came from a tank that was lit by xm250 20k's that might have been on their way out, and now they are under 2x24 t5's for 5 hours a day...

TIA