actually i don't believe dropsy is a result of poor water.
I believe it is more a problem of organ failure than poor water.
typically , Sx is swelling and may be edema , end result is usually organ failure.
but have seen it occur in pristine water conditions on some species of fish.
You could be right, sadly the fish died earlier this morning, I wonder if due to him losing an eye he was infected with something quickly. Sunday morning he was fine, not eating, but I had put that down to him adjusting to only having sight in one eye. Later in the day I saw him laying on the bottom of the tank.
Somewhat of a crap week really, lost my job Wednesday and then lost my biggest angel fish today.