Big zoa die off following PO4 spike

[Keko21]

Just venting. I just had a massive zoa die off following a big PO4 spike My system has always run relatively high phosphates Hanna checker typically at .12- all corals were flourishing and happy. Something triggered a pop and they went all the way up to .3! Most of my corals are fine, surprisingly the SPS seem to be doing the best right now, but I have a candy cane, 1 of 3 gonis, and ALOT of my zoas which were very large colonies which have been shriveling up. I got the phosphates back under control and I am reading at .09ppm currently. Small groupings of polyps of various zoas seem to have survived, I am just hoping they bounce back and start filling in again and don't continue to disintegrate. Sigh....
Current Parameters:

Temp 78*F
1.026 salinity
14ppm Nitrate
.09ppm Phosphate
8.4pH
481ppm Calcium
1270ppm Magnesium
12.1 Alk

 

[Formulator]

I don’t think the phosphate is killing your corals. Something else is going on. Many older tanks run phosphate above 1.0 or even 2.0 ppm. Softies usually like that anyways. What caused the phosphate to spike?

 

[Lavey29]

I agree with the above. My phosphate just elevated to .79 and all corals are fine. Tons of zoas.

 

[Keko21]

I don’t think the phosphate is killing your corals. Something else is going on. Many older tanks run phosphate above 1.0 or even 2.0 ppm. Softies usually like that anyways. What caused the phosphate to spike?

Not 100% sure. I'm a heavy feeder but always have been. My coral food is Benepets which really has minimal effect on PO4, and that only goes in 3 times a week. Skimmer turned off for a day (I forgot to put it back on after a water change). PO4 is the only measurable difference that I noticed when the zoas started to die off. And again most of my other corals including euphyllia, mushrooms, and other softies and SPS are fine.

My best guesses are there may be a deficiency or spike in some other trace element that I dont test, or some kind of disease got introduced somehow, I haven't added anything in a while though...

 

[Keko21]

also an interesting note is that some zoas are definitely doing better than others, green people eater palys- unaffected, eagle eye zoas unaffected, but some of my big red and pink colonies are down almost 50%.