walt did you stock fish in those? If so they are dead OR you proofed Cecil's point a meter can be wrong. Seriously 1 ppm is bad news rarely do we see that, something strange to cause issues like that killing watermeal will not do this alone.
If you put fish in that they should have instantly came to surface. i have doen it only once, it was like the water was on fire grass carp were jumping out of the water.
