Sorry to hear this Vincent. Do a quick check on your KH. Not sure if it's QC problem or some shop selling "expired" TM salt, I suffered same thing last month. 2 colonies STN.
Reason: sudden drop of Kh (during water change).. I measured the new saltmix, and kh reading was a low 3! And ca only 250++.
As a result my tank's Kh is only 6... Very bad. I kinda gave away the entire bucket of salt.
Btw I have a ready frag of chilling pepper, stable and growing. Let me know if you need k.