This I think could happen. I dont know - but its plausible. Like I said before I was never questioning what happened to you - I was questioning how it could have related to the OP:)I think you're missing my point. I'm not sure how the condition was met, I'm just saying that it currently is in that condition and that if the condition is met it is possible to have the alkalinity raise on its own.
What I imagine happened was in the earliest stage of the nitrate problem happening his alkalinity probably lowered and he corrected it by adding 2 part. Eventually when his nitrates were lowered rapidly it added the additional alkalinity that he can't account for. In my case I dosed 2 part to compensate for a sudden drop in 2dKh and that 2dKh would eventually have been replenished, thus resulting in an increase from 9.5 to around 12dkH.
