Mike,
That's a real good sign when your brook trout don't have a problem getting thru the summer. I don't know anything about chara, but what can you do to control it?, would horizontal water flow help.(like using a trolling motor,or pump? I'm lucky I don't have any problems with weeds.
You mentioned having 23" rainbows, they must have been fairly heavy, did you weigh any of them?, and do you think the golden trout are more susceptible to predation?, i read that somewhere.
Good luck with your cage, are you using plastic netting?, I bought some at lowes this spring, and made fish traps with it. -- Larry
