Well, I had not checked my mag in a while so i somewhat forgot how to read the red sea test kit results. I read them backward, so i thought my mag levels were under 700. I dosed about a gal of mag (BRS 2 part) in about a week. Levels had not changed.... so i watched the red sea mag youtube video to see if i was doing something wrong. That is when i realized i was reading the results backwards. My mag wag over 2000 off the results chart!!!! Panic......

i had noticed all my snails were falling off the glass and frozen, some were half out of their shells, my star fish were not moving - i thought they were all dead. Researching, the effects of high mag cause the inverts to basically freeze or have this drunk effect to where they do not move because they are disoriented.

The last two nights I have done about a 25% water change. After the 1 water change, all inverts started to move again.

One thing I noticed is that I did see some precipitation in my sump. I had to clean my return pump drive shaft as it was starting to get build up from the precipitation. I could tell this because it was vibrating pretty loud. Once a quick soak in vinegar, shaft moved freely again and a silent return pump again.

All corals and fish did not seem to be effected in any way.

I had 1800+ mag levels when I treated for bryopsis with Tech M a couple years ago. Basically saw the same effect on the snails you did. Only other side effect I had with the Tech M was a slight bleaching of my montiporas, just a lightening of color, nothing completely white, and they all recovered in a couple weeks. Whether this was an effect of the Magnesium directly, or the trace in the Tech M that actually kills the bryopsis, not sure?