losing sps frags

[cbs49er]

Hello, so I've been having a problem with my sps corals. I was gone for vacation for a week, and when I got back 3 sps frags were almost completely white. I thought maybe they left the windows open and something spiked. The following week I lose 2 more, one during the week and one the day after a water change. I have a 25 IM lagoon, I only use filter floss, dose 15ml of all for reef daily, benereef 2/week, amino acids 3/week, reef roids and phyto right before weekly water changes. These are my parameters right now a day after my water change.
Alk 7.8 Hanna
Phosphate. 03 Hanna
Ph 7.8 Api
Kh 13 again 12 Api
Cal 415 Salifert
Nitrate 2 Salifert
Mag 1110 this is usually 1250 Salifert

not sure if it's pest but I always dip new corals and I also have a springer damsel which are suppose to eat flat worms. Thx for the help

 

[Krux]

My first reaction with sudden die-off or dramatic changes is to send in an ICP test to look for contaminants or a big difference in what I am getting on my test kits.