I have been successful this year in producing 3-1/2 gallons of liquid gold (up from 3 gallons on my inaugural year last year) on my block arch / 7 tree tap bucket system. I have encountered niter in my syrup this year in my jars of which I had none last year. I have read to let settle and pour off top leaving niter at bottom and then re-package. I have 3 question pertaining to these suggestions:

1) Do I reheat or re-boil top of batch syrup prior to canning? At what temperature should I process this to can and should I re-filter?
2) Do I assume that I take the syrup contaminated with niter and re-boil to density (I use a hydrometer) re-filter and can?
3) At what temperature does niter begin to occur?

I have found this hobby / obsession to be quite enjoyable not to mention, DELICIOUS! I often times think back to the early inhabitants doing this using hot rocks to boil the syrup. And we think that what we are doing is work?!!!