Fish are dieing - don't know why

[naesco]

Originally Posted by Frenchie

Monday my yellow tang died. Yesterday my fox face went.

Its strange because they show no signs of illness, hours before their deaths they were eating and acting normal. And all the coral looks great.

I have been trying to raise my kh with the brs 2 part mix, but I only added 50 ml?

Could my blue tang be killing them? Hes alot bigger then they were.

Parameters are as follows

Ph- 8.2
No3- 0
No2- 0
No1- 0
Phosphates - 0
Ca- 420
Kh- 7.5
Mg- 1200

I'm stumped... and crushed!

I am sorry to hear of the fish loss
What kind of `blue`tang do you have and when did you add him