I do not use drums for processing, but there are a number of people on the large format forum who do. You might ask this question there. The Rollo Pyro formula was developed as a substitute for PMK specifically for use in drum processors, so you might give that a try. I believe the formula is on the Jobo site, and I have reproduced on my own site as well:(posted 8628 days ago)http://unblinkingeye.com/Articles/Developers/Formulas/formulas.htm