I tried some please release me and hydrogen peroxide as was suggested by a bass buddy and it killed em quick. I had problems with plugging the Livewell overflows in my boat but once I got them plugged off good so the water didn't all run out everytime I moved I have had better luck keeping them alive. I fill them first thing when the water is coolest and recirculate all day. Hopefully we can check fish in early next 2 tournaments like last year.
If you use any of the keep alive or release me type products, make sure it is fresh. If you bought it last year, I'd discard it and get fresh. I fill early and recirculate all day. Add some frozen bottles to cool slightly.
Don't cool too quickly or too much. I pulled out of the water in July with fish and decided I'd help revive them and added the ice from the cooler to the live well and headed to weigh in. Opened the live well and all 8 fish were laying on the bottom. I panicked. Got a 5 gal bucket with lake water and put the fish in it and they revived luckily.