Cecil - I've ignored your post due to my ignorance of trout (a double-negative?). In any case, glyphosate "should" be safe for treating cattails in a trout pond - if necessary. BUT, you'd best check with local herbicide/fisheries specialist on that matter, to be certain. Regarding the other species mentioned: chara will likely be very tough to control with an algaecide without posing a threat to your trout. You might check on the prospect of using REWARD (diquat) rather than a copper treatment. The Poto's; maybe the same product would give you some relief.
Not exactly definitive answers; just some guidance for direction. Let me know how it pans out. Good luck. Kelly