Just a heads up...if you buy Campden tablets from Amazon you need to look closely to see if it's K-meta or Na-meta. Fool me once...
but, yeah, what is in those fillers? .
Thanks for the infoMost folks use Campden for small batches, 1 or 2 gallons, maybe 3. For larger batches, powdered K-meta is easier to use, and IIRC, it's cheaper than Campden.
I follow the old rule of thumb which calls for 1/4 tsp K-meta per 5/6 US gallon carboy at each racking. I use a 1/8 tsp measure for 3 gallon carboys, and rarely make smaller batches.