Tank is crashing :(

[tang daddy]

How long has your tank been set up?

When did you introduce the acros or they grew from frags?

Doesn't look like a lot of rock in the display, could this be happening because of a lack of nutrients/bacteria?

If they only started dying when you changed your t5 to led it is a possibility that it was the light but even usually if it's the light it takes a bit of time i.e. Bleaching, stn.

Did you check to see if predatation is a factor?