Got the urge to test the tank tonight before a water change, and ITS A GOOD THING I DID!! Holy crap, hopefully a crises diverted but time will tell.
It started by looking at the temp, which I always check my thermometer vs. my chiller reading for accuracy, and found the chiller was powered off (for who knows how long). A little investigation shows a blown fuse, which will be replaced in the AM, but temps were still in line so no worries.
Next step showed pH reading down at 7.9, the lowest I've ever seen in my tank, but I thought maybe it was because of taking water just after lights out (and associated pH drop). Such was not the case...
All organics were inline, but measuring Alk freaked me out to the point of taking 3 retests. It was reading 3.5dkh... Ya, 3.5dkh!!!! It took a bit to purge the alk line from the doser, so not sure if it was clogged or if a bubble had just unprimed the doser, but apparently the tank had not been getting any alk for a while. Subsequent Ca test (as you would expect given ca/alk linear relationship) was wicked high at 610. The Elos Mg test reading was funky compared to normal (40 of A and 8 of C, vs. the normal 35 of A and 5 of C, Elos users will get it) though it resulted in effectively the same end reading. The alk just threw the test off.
Anyway, just about everything seems no worse for wear surprisingly, the clams all look great as do the corals. I finally decided, however, to ax the ORA green stylo which has been slowly fading, sad to see such a large but mostly dead colony. The exciting part is that once I get things back in line I'll have room for new corals (and hence motivation to maintain the tank).

I see a cool stag or table acro filling up that spot sometime soon.
