This has worked well for me this year and I have fished 2 tournaments in the last 2 weeks with the hot temps. I take 3 seperate frozen gallon jugs and keep them in my cooler. Once I have fish and the temps start heatting up for the day I will add one jug at a time to keep the water cooler. The three jugs have been enough to keep the water at least 10 degrres cooler for the whole tounament. Every few hours I will pump fresh water in to flush out the livewell but mostly recirculate to keep the temp cooler. I have not lost a fish and have had 5 fish in a livewell for the last 4 hours of one of those tournament. I use the milk jugs because of the concern for chemicals from treated water mixing in the water effecting the fish. When one jug melts, they usually last about 2 hours each will change them out. This is the only thing tthat i do and have not lost one fish this year or ever. I'm sure the additives work but I like to keep it as natural as possible. When releasing the fish treat them as you were bring in fish to add to an aquarium, keep them in the weigh bag and hold the bag in the lake water for a few minutes so that they do not get a shock when releasing them back to the warmer water. They have all swam off rather aggresively. This works for me.