Actually, to be clear on this, I believe that the bigger the tank and the more film present, the more 100F short presoaks should be used. This is to prevent chilling of the presoak water by large masses of tank and film. So 200 ml 2x for 30" each might be good for 1 - 4 rolls on up to 2 or 4 reels in a small 1500 series or maybe even a 2500 series tank if it covers the film. But, if you get to 4 - 6 rolls of 120 or 220 in a 2500 series tank or a 3000 series tank, you may want to think of up to 1 L or more water in 3 or 4 15" or 30" presoaks. The larger the internal mass in a tank, the more it will offset the temperature effect of the presoak water.

Just some kind of afterthoughts on this subject.

PE