50 lbs of feed/month in a 1.5 acre pond is not too much feed on face value, but you may have something else going on. Feed also converts to fish poo which can affect water quality.

Water turning 'dark red' is not good, so maybe you should stop feeding for a few days, and see what happens.

I don't know if there's a way to have the 'red' water tested to determine exactly what it is.


Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."