You are going to want to remove all ink from your screens before you put them in your tank. Companies tell you that your ink will come off in the tank, but you will find you are creating more of a mess, losing potency of your chemical, and you will have to remove gunk build up at the bottom of the tank weekly and continue to add chemical to keep your potency up. Also, not removing ink first slows down the ability of the chemical to directly reach the emulsion.
We, card off bulk in, de-tape, de-ink-we use beenie doo in the booth, then, once that process is done on a load of screens, they go in the dip tank, 3 at a time. This process goes very fast for us, my screen guy does an average of 30 screens in a 2 hour period from carding off bulk ink, de-tape, de-ink, then dip, pressure wash, degrees, and rack. We use SPA chems, and have had the best of luck with them over Franmar, and Easi way which we have tried in the past, they are lower in cost too.