Mike,
Last year i put in a pound of rid-x, but it didn't have any effect.
According to lab tests the flush-it has 8 times more bacteria than zep enforcer per gram, but 1500 times more than rid-x. I paid $65.00 for a pound of flush-it, so the zep enforcer might not be too far off in value if it's under 10 bucks a pound, but the rid-x doesn't seem to be worth it.
Of course thats if the lab data is correct, they have it on their web site.
I haven't seen any osprey around here, when i lived in Virginia we would see them alot on Green mt. lake.
Good luck with the chara, I'd like to see pictures of your pond.
lARRY