Redfinger,
the only time I've seen chara become a problem is in clear lakes that lose water fairly rapidly. That said, it can happen. Fertilization usually controls it well.
grass carp are listed as providing 'good to excellent' control of chara in the 2002 North Carolina Agricultural chemicals manual, chapter 8. I haven't seen chara become a problem in ponds stocked with grass carp in Texas. One lake that had a severe chara infestation was essentially chara-free the year after stocking 7 carp/acre and fertilizing.
Because chara is often in a band close to the bank, it is my experience that liquid cutrine can also provide good control.
Your results may vary
