So I am a little confused. So I am going to try developing my first roll of b&w film with Rodinal. The dilution recommended is 1:25 I have a Patterson Universal which I understand holds 500ml. How do I calculate 1:25 for 500ml? Is it like this? 500/25 = 20 500 -20 = 480 So that would mean 20ml of Rodinal go into 480ml of water? Or am I totally missing something here?