I've started shooting some underwater macros in a freshwater stream using a plastic bag housing (EWA Marine UF). Pentax K1000, 55mm Takumar on a reversal ring. Tomorrow, I'm going to add in a strong yellow-orange or a Red 23 to cut blues based on the conditions I observed. I was using Ektachrome E100G at 100ASA. A lot of the shots today were at f/4; I want two more stops for DOF alone. Add in that filter, and I will need three to get what I want. Today's film is undeveloped, but I know I need some improvement in it. I can feel it happening. As I looked at this situation, I just felt like I should be using about 1000ASA film, or slightly faster. I could pull that off in black and white, but I want to get it done in color slide, E-6 home processed. The project requires film for my main shots, so I'm nixing the digital option. It's a ways out there and back, so I kind of need a plan for improvement that has a reasonable amount of security. Extensive testing in the field is not really the best option. What are your suggestions? Can that Ektachrome be pushed two stops? The tech pub only has guidance for a one stop push. Got another film type suggestion instead? I'm going to want E-6 color reversal; spooled to 135 format. My goal is to find something that would behave like 1000 or 1600 ASA films, but in color reversal. I feel like that would be the right answer, but the products I'm familiar with don't do that. Your suggestions?