Baking soda = bad?

[asylumdown]

So not too long ago I ran out of the 'reef grade' powdered carbonate, so in a pinch I went out and bought some unscented arm & hammer, as it's essentially the same stuff. I used it to make the last two gallons of auto dosing solution. (has been the primary carbonate source for approx 1 month).

In he past 10 days, some of my sps are starting to look like everything did when I had a massive alkalinity crash (pre-auto doser days, when I had left town for 10 days and the person taking care of the tank wasn't manually dosing), and I lost about half of my coral. Their tips are losing their 'fleshiness', turning white, and burning in some places.

All my alk readings are normal though:
dKH: 9.8
calcium: 420
Magnesium: 1300
pH: 8.2
ammonia, nitrite: 0

The only other thing I've changed recently is that I added a biopellet reactor and a carbon reactor. Not sure if a sudden stripping of NO3 can do this

Is it possible that the baking soda is the culprit, or would the biopellets & carbon reactor be more to blame? Everything was growing like weeds until this started. I had been running carbon in the sump before, just not in a reactor and added the biopellets because I was having some algae problems.