I just racked into my secondary. I initially put a campden tab in when i made the must (1 gallon). I did not use any for the secondary. they say to add every other racking and then at bottling. so my next racking i would add a tablet, next racking no tablet, next racking tablet then bottle or wait another month then bottle. my recipe actually says to let it sit for 2 months after the secondary. honestly i think it would just be much easier to test SO2 levels and adjust at every racking for it unless it's very complicated. i've never done it before but my wines always could taste campden. oh, also i've got a complete 750ml bottle of left over must. do i keep up with rackings on this as well for top ups or can i just let it clear in there and put it in the fridge or something?