battling red slime

[GPB]

Rinse the mysis in RODI water (drain out cloudy water into sink) first before tossing in tank.
Get PO4 test kit.
Get nitrate kit.
Get GFO.
How much flow do you have in terms of water turnover.

There's a nutrient problem somewhere.

 

[CoppBandbuttfly]

the red slime is still there, all large fishes died recently, but i doubt if it was caused by the red slime. Right now 2 false crown and two chormis left. I would like to tackle the red slime again before I buy new fishes. I will look at your suggestions re GFO, PO4 test kid..etc.