I have a really cute rainbarrel that I use for watering my flock inside and outside. It's your typical 55 gallon drum, painted up really cute. last year I had an issue with the water being in the drum to long and the girls would not drink it. It was not sludgy, or alge like. Just old and stale I guess. Is there anything I can add to the water to keep it good? I have been told to add a few teaspoons of bleach into it, but I am afraid to do so.