Nutrition questions/thoughts

Hey folk-- Having done several o.w. swims, including three that included food stops, I noticed a few things and want to compare notes: 1. As both runner and swimmer, I noticed that things that agreed w/ me when I did long runs caused digestive issues (to put it gently) when I swam. For instance, gels that were fine for running made me very uncomfortable when swimming. At the same time, something like Muscle Milk (I know, I know--tell me how bad the ingredients are, etc.) worked great for a 6000 yard swim... but I wouldn't use that for running. And the "Nu'un" tablets you add to water for electrolytes... fine for running... forget them for swimming (well at least for me... maybe others have better experiences?). So why would something that works well for running not be so good for swimming (and vice versa)? 2. My nutrition plan last year (practiced on a 3 hour o.w. swim w/ my coach) was perfect... in fresh water. In salt water... some things that I could digest w/out trouble in fresh water gave me the heaves in salt water. Live 'n' learn! So... what have you found in this regard? Differences between running and swimming? Between salt water and fresh water? What seems to work best for you in salt water especially? Thanks for your thoughts!