Colleen, the bottom of your tank should say how many ounces or ml it takes to develop a roll.(posted 8692 days ago)Mine says 10oz for one roll of 35mm. For a 1:4 ratio that means you mix 8 ounces of water with 2 ounces of developer. If you were developing two rolls, it would be 16 ounces of water and 4 ounces of developer.
chris