Rain barrel

[PoolDoc]

The local nursery folks advised that the salt content, over a long term (a year or so) can cause the effects we were seeing. We switched to well water and after a few months the health rebounded.

Makes sense. Indoor plants lose water to evaporation, so all the salts and minerals in the water used, end up staying in the pot soil. Outdoors, rain flushes those accumulating salts away. So, no problem. Indoors, a little more salt accumulates every time the plant is watered, resulting in problems.