Help!! SPS starting to RTN

I suspect Alk might be the issue. That is a pretty big swing in one day and corals don't like that one to change much. We lost a number of corals when our kalk top off stuck on and alk shot up (even more than yours did). I agree, if you get it stable they "should" pull through if they are still alive. IF some you really like are R/STNing you might frag one and put in another tank as insurance. Good luck it sucks.

Must be the day for tank disasters. We (think) we had a sea cucumber get sucked into skimmer pump and we lost almost all of our fish. Devastating.

 

Chris - good luck with the rest of your corals.

Dave - how awful!!!!!!

 

Sounds like your on the right track. You may have more pissed corals over the next week or so.

I am guessing the low magnesium started it all and the alkalinity swing finished off anything that was stressed.

It is recommended to only raise MG 100ppm/day, dkh .5/day and calcium I can't remember but thinking 50ppm/day.

I had same problem and nuked my whole tank. I had a few other factors added to it but pretty much same situation but my alkalinity went from 7 to 9.8 and my tank is urns. So anything over 8.5 and I have tissue loss.
Take it slow. Get your Alk a little over 7 your calcium 380ish and MG 1250 or more and see if you can keep it stable.
Hopefully only good things from here. Good luck. Keep us posted.

Was tissue loss from the base then spread or just patches of flesh peeling from all over?

Can you test po4?

 

I'm so sorry to hear that... That's terrible news. Was this on your 300g DD or the 200g (or 220?) in-wall?

 

300. Two clowns and mandarin are the only survivors.

 

Dang that makes me feel sick! That was such a beautiful naso.. and powder blue. Bleh.

 

How the tank looking now Chris?

 

Have you checked your salinity with a calibrated refractometer? I'm stunned you were able to get all of your levels that low.

 

Another thing to consider is to use salt water for your top-off water - until you get salinity back to where you want it to be. The salt water could even be at a slightly higher salinity. This would slowly increase your salinity as well as increase your calc, alk, and mg levels.

 

Was your salinity around 27 ppt by any chance? That's roughly the salinity that your Ca and Mg would be lined up with. Makes things a little easier if you don't have to raise salinity while also calibrating certain parameters.

 

Conductivity probes are worthless imo. I too would look to bump the alk a little higher, though I would like to know the po4. I recently kept track of my tank over a few months and noticed it hits 6 for alk since I've been slacking on tests. It was looking just fine though, that's what made me wonder. But after bumping the alk up 1-2 dkh in a day or two, I still had some necrosis on one specimen.

One thing I always do if I ever notice necrosis is feed extra everyday with nutricell. You could probably use any particulate, but this is encapsulated. Coating the corals in food seems to help halting or at least easing the stress, whatever it may be. But also do a very slow in/out with a water change over the period of a few days will help deal with the extra food.

In hindsight, as I've been doing more testing with the tank looking great, I noticed 6-7 dkh and .1 po4 on a regular basis. Minimal algae still, but colors have faded just a tad. But of course the alk would tank (ba dun ching!) if there was a catastrophic event of some sort.

 

With po4 being on the high side you may want your alkalinity up around 9.