I develope GP-3 for 14 mins at 70f, very good film for the price, and the fact it's Chinese. I have a large stash of 120. Five minutes for water stop is too much, 60 seconds maximum, or two 30 second rinses for stop would work better. I like to use acid stop diluted half strength followed with 30 seconds water rinse then fix in TF-4 for two minutes. The water rinse only helps prolong the life of my fixer.