I hoping to benefit from someone else's experience. I went to the garage cabinet where I store my pond chemicals to mix up some liquid cutrine for some FA spot treatment. The unopened gallon jug 'rattled', as it seems 'something' had precipitated since I'd bought it last year. WAG would be the copper had come out of solution? Anyway, I took to vigorously shaking the jug, and while I was able to break up the clump of precipitate, it would not dissolve again.
Question: Should I dispose of this or use it anyway? I doubt it would cause harm if the copper had precipitated out, but don't want to waste the effort of spraying with 'bad' cutrine liquid.
I was just wanting some experienced opinions before I waste a $50 jug of cutrine.

I believe copper is the active ingredient in cutrine. If it drops out...what'soing to kill the weeds?

Cutrine Plus pamphlet quotes...

"ACTIVE INGREDIENTS:
Copper Ethanolamine Complex, Mixed (Mono CAS#
14215-52-2 and Tri CAS# 82027-59-6)*..........27.9%"

"This product is a liquid copper-based formulation containing ethanolamine chelating agents to prevent the precipitation
of copper with carbonates and bicarbonates in the water."

From...

http://www.lakeandpondsolutions.com/media/34102/cutrine%20plus%20label%202012.pdf

Even though the "ethanolamine chelating agents" are supposed to keep the copper from falling out, something has solidified and I'd bet that those ingredients are important to the nature of the herbicide.

Disclaimer - I'm no herbicide expert or cutrine user for that matter. Just my opinion...I would dispose of it or use it with little hopes of any killing effect.

Yeah, seems like the best/smartest route to go. The FA and duckweed have been killing me this year. I was pushing myself around the pond in the canoe (which slips over the FA mats best) spraying, and a field mouse suddenly appeared (from the float compartment in the bow or stern I'm guessing). He was pretty tame, so I just picked him up by the tail and flipped him out into the pond. The FA mats are so dense, he was able to (mostly) walk back to shore! He even stopped for a rest and a drink. Sad stuff. I'll keep after it.
Thanks for the input Quarter!

I had the same thing happen after a half full jug froze in my garage. I shook and shook and then added the solution to my sprayer. (Left the solids in bottom of jug)$!. Then I added another half gallon of water to the jug and did the same thing about 5 more times. In the end, there was a small amount of solids in the bottom that I discarded. Then filled the tank to the prescribed level and sprayed as I always do. It seemed to work fine. Not sure if that was the right thing to do, but I saw no I’ll effect and it controlled the FA well.