Nutrition/gels during open water races

Hey all, I'll be swimming in a 5.25 mile race in August... I'm trying out different gels and wanted to get some input from those of you who have done longish salt-water races. I have a good sense of the gels that work well for me when I run, and a recent experience with one such gel during a swim workout made me especially aware that a gel that works fine for running might not mix as well w/ swimming. I took a vanilla flavored Powergel about 45 mins. into a longer swim, and while I digested it w/ no problem and got some energy from it, I noticed a stronger vanilla aftertaste than when I used the same gel for running (exhaling vanilla flavor, you might say). This didn't bother me too much, altho I wondered how I'd like that aftertaste for four miles...--but I wonder if the mixture of taking a gel w/ swimming in chlorinated or salt water affects how the gel works in one's system. For those who both swim and run, do you find you need to use different products when swimming than when running or have the same types of gels and sports drinks worked on both land and water? If this is a totally newbie question, thanks for bearing with me!