Just a note to always check the ppm levels of your campden tablets.
ppm = parts per million
when i began making wine, it seemed like all campden tablets were 50 ppm, which was nice because most of the charts that show how many campden tablets to use depending on the pH of your must were based on 50 ppm.

this fall when making some wine with fresh juice, after sulfiting, waiting a day and then pitching my yeast, it took 1.5-2 weeks for ferm to start in all 8 batches.
this bothered me for months, then a week ago i looked at my bottle of campden that i just bought and it said 150 ppm!!!!
i had added three times the campden tablets. that's a clean must! the problem comes in right around now when i am battling hydrogen sulfide issues from the stressed out yeast and too much sulfur. not to mention the obvious issues of what would have happened to anybody that may have pulled a sample of that ferment and tasted it. that is way way above the acceptable level.

i would advise everyone to avoid these high dose campden tablets because it would be much harder to adjust based on pH. you would need to cut tablets in half, and that is never advised because of the inherent margin of error. being a curmedgeon, i wrote an email to the very popular internet site that i ordered them from asking them to please making it easier to find out ppm levels if they plan on selling multiple strengths.