SDK, honey, have you ever enjoyed that fresh clean air after a rainstorm? Have you ever wondered where all the smog goes after the rainstorm? It is in the rainwater! Now if you live in a nice rural area, it wouldn't be so much of a problem. If you live in the smoggy city, it might be wise to only collect it after several hours of rain. My plants flourish using aquarium water and a bit of mollasus. Never burns the plants. My plec is about 11 inches long and he and the Dempsy spar a bit now and then. They both produce a large amount of fertilizer and the plants, including my orchids, love it.