Sorry for the delay responding. I was adding the lime by diluting it in a 5 gal bucket then adding it about one gallon a day. I have stopped using rain water and am just using tap water now. Things have straightened themselves out and everything is back to normal. The fish are back to their vibrant selves eating like piranhas. It looks like the low PH of the rain was the problem.

Thanks for everyone's help.
Harry