Can calcium/alk swing kill my corals?

I was away for christmas for almost 2 weeks and came back a healthy tank. I performed a 25% water change with my new RO/DI, cleaned my filter. tested water and added some calcium and alk supplement. 1 day later monti is dead all my zoa's are perma closed, GSP even not out much, torch coral almost completely retracted. The monti is white a bone so I'm assuming its dead. The odd thing is my clam and acropora looks healthy as can be, no bleeching, great polyp extension.

Only thing I can think of is if (kinda wish I tested before the water change now) my calc and alk were very low and between the water change and the supplements it got raised too quickly. FYI the monti wasn't more than 2 square inches. I have not reached a point where they draw a lot out of the water.

Is this a possible reason for the dead corals or am I way off base?

and by the way just because I know its comming
Salinity 1.025
calc: 420
mag: 1380
Alk: 11
ammonia 0
nitrite 0
nitrate 0 ish, hard to read

 

well sps are very picky about the alk... and if the swing was too much then yes, it will make them mad and possibly stress them to death.

 

zoas are affected too, so is it possible I should be looking for a different answer?

 

no although the zoas will probably live, im pretty sure its alk is what killed the sps. Surprised that your acro is fine though.

 

+1 to alk swing.

BRS recommends raising or lowering 1 dKH per 24 hrs. My acros don't even like that much of a change.

 

I had this happen to me before, I added my sump and had not mixed the new salt water which I had put into the sump to get it going enough. When the return pumped it into the DT, my water clouded up and I lost my digitata, trumpets and leather. However, many things did survive. More recently I had Ca or alk precipitate out b/c I added too much alk at one time. This didn't cause any damage and everything was fine, the water was just a little cloudy for a day or so.

 

thanks for the replies all. Is there anything I could do to help them along or just wait to see who makes it?

 

Any swing,whether its Alk, Cal, Mag or temp is not good.


luna