I am new to using a drum roller system. I have a 16x20 drum and have 2 questions. 1. Any idea how much chemical (oz) to use to print 1 print. Using developer for 1 shot don't want to waste chemical also want to get max use. 2. Also this may be the wrong place to ask this question, I'm obviously making 16x20 prints and my exposure time 4x5 neg f11 w/ 2 1/2 multigtarde filter are 90 sec. Negs look pretty good, if anything little light. Does a multigrade filter make that much difference.