Slojmn, sorry to hear of the malfunction.
I had a doser hang in the on state a little over a year ago. The pictures are what my tank looked like in the morning.
It dosed almost a full gallon of Alk into my 150G during the night. I wasn't sure what to do and performed a massive water change since I figured I caught it quickly. I changed over 50G before I could start to see the back of the tank. It was like whole milk. While I lost most of my chalices and some of my acros, I only lost one fish. The acros faired much better than the LPS. It was a long process and I believe my tank is only now starting to make a come back. Hang in there. JP