I did. Yesterday Mg was 1480.

Update:
Today, the Alk was 9 dKH and the Ca 420. The Alk doser has been unplugged for 48 hrs now, so the alk levels are sustained at 9 by my kalk additions alone. I am still dosing the same amout of CaCl2 solution as ever....

I'm still puzzled as to why this imbalance occured. The STN wasn't severe enough (I didn't lose masses of corals) to radically reduce Alk consumption. The STN seems to continue (I fragged a couple of pieces to save some SPS). Still, for over a month I seemed to have dialed my levels with equal Ca and Alk solution additions on top of the Kalk addition at a fixed rate. That's why I am so reluctant to take the kalk offline.

What I would like to know is why, all of a sudden, Alk levels started to increase after more than a month of the all the parameters being balanced and steady. Has anybody else experienced this?

It's not hard to figure out , 8.5 to 9.0 isn't a big jump in fact it's barely out of testing noise . In any way you look at it alk declines only when being used , why these animals stopped using as much as they did could be many but the fact remains that in order for alk to rise you had to of added it , if the amount added doesn't equal to the amount used them bam a rise in alk

Calcium will follow they same rule only you won't see the difference day to day but may weekly.

So either the tests were errors, you added more alk than normal or animals stopped using it for whatever reason...it's as simple as that so you'll need to adjust accordingly

I didn't change the amount dosed. I watched the alk climb steadily over a week. After being steady for a month or so, between Nov 1 and Nov 8 it went from the 7.6 - 8.2 range to 9.0 - 9.6 range. That is significant. I was still dosing the same amounts of Ca, Alk and Kalk automated via my Reefkeeper. That's what is so puzzling...

So, clearly the tank inhabitants stopped using that much. Why?

Maybe not solely but when stuff doesn't go right they shut down consumption , don't put pinpoint faith in your tests or your kalk either . I'm not sure why the corals would stop using it in your system the reasons are literally endless but it happens.

Update
 

Thank you guys for all your thoughts. I am now running the tank with Kalk and CaCl2 solution additions only. The Alk dosing pump is still unplugged. The Ca levels are good (400-420) and the Alk is somewhat stable too (8.6-9 dKH).

Yesterday I checked nitrates and phosphates too and they were both zero. I did notice that other acro colonies are STNing from the base up. I just wish I knew what is causing this. Watching colonies STN helplessly is painful....

If running biopellets you may need to have ur alk in the 7-8 range. Many people that run biopellets report STN with alk levels above 8

Quick update: I finally broke down and took the kalk stirrer online. The Alk solution part of the two-part was offline for a coupl of days before that. The alkalinity took a couple of days to fall to today's range of 7.6-8.2. Which leads me to think my corals have shut down. What puzzles me is that I am now only adding Ca solution (part one of the two-part) at the same rate as before the STN started, and I can barely keep the Ca above 400.

I noticed STN startingin in a couple of other acros, including my green slimer. This is truly tragic....

if you cut out the kalk but kept chloride the same as before the stn then your dosing less calcium as the kalk had calcium in it too so the chloride dose would need to be more to be the equivalent of both.

small differences in calcium are hard to control and test for ....it takes 1-2 weeks just to get an accurate consumption rate as the differences daily are to small.

sucks man every sps guys future and nightmare :)