One think I found is that I got better results from using a two reel (500ml) tank than my four reel steel tank. When I did four 35mm films I got some streaking. I did another four films with a pre soak and a little streaking on four frames or so. I think it was taking too long to get the developer in, and the extra 10-12 sec was streaking film as the developer ran by. I haven't gotten any streaking from my 500ml steel tank or my two reel Patterson. If I had a proper darkroom, I'm fill the four reel tank and dunk the film all at once - I don't, so I have to pour through lid. Just my experience.