Ricordea and another shroom melting

I just came home after being gone for two days and I found my blue ricordea and my red mushroom covered in brownish slime and completely retracted. The red mushroom has broken into three pieces but still has a bright red color. I had both corals for only 4 days before I left for the weekend but they looked great during those 4 days. Anyone have any idea what could have happened to them. I have them both in a mid/low level in my tank under t5s and low flow.

I did some water test and here are my findings:

Ammonia-0

Nitrate-0

Nitrite-0

Ph-8

Phosphate-.25