Hi everyone,
I just got the second rain results. I will post both sets of results.
The first water batch had several bits of brown organic material in it, which looked like tree detritus. The detritus must have been in there for at most 4 hours.
pH = ~7.0 (my scale goes down to 7.4)
GH = 25 ppm
KH = 40 ppm
NH3/NH4 = 0.25-0.5 ppm
NO2 = 0 (not detectable)
NO3 = 0 (not detectable)
PO4 = 4 ppm
Ca = < 200 ppm (not detectable)
Note the very high phosphate and ammon. level.
Now when I collected the second batch of rain water, it had only 3 tiny chunks of organics in it, which I think were pieces of tree leaves in the water for at most 1 hour.
pH = ~7.0 (my scale goes down to 7.4)
GH = 25 ppm
KH = 40 ppm
NH3/NH4 = 0-0.25 ppm
NO2 = 0 (not detectable)
NO3 = 0 (not detectable)
PO4 = 0.2 ppm
Ca = < 200 ppm (not detectable)
In the second batch, the phosphate and ammon. levels are much smaller. My ammon. test kit stinks, so I'm not sure how accurate that measure was, but it was surely smaller than in the first batch. So if you collect water for tank use, which I still don't recommend, make sure there are no organic chunks in it. Otherwise, algae will love you.
It appears that the water is pretty neutral in pH. At first I was surprised at this, but then after thinking about it, I guess most of the rain here comes from clouds that formed over the Pacific, and therefore San Fran. Bay area pollution has not really had a chance to make the rain acidic.
This was fun. Thanks.
sam