Question
Is there a simple way to test for zinc in the rainwater that runs off my roof into my rain barrel? I use the rain barrel water to water my CPs and the plants do ok but I'd like to make sure that the water isn't harming them. I have mostly pitcher plants and sundews that are getting full sun.

Answer
Hi Scott,

You'll need to use a total dissolved solutes (TDS) meter.  They're kind of spendy, and it's not specific to zinc.  It'll measures the total mineral content.  You can also take a sample of your water to your local aquarium store.  They usually test your water for free.  If not, they sell test kits.  The kits aren't as specific or accurate as the meter, but it'll give you a general idea about your water.

You could find out what type of roofing material you have, and then check with the manufacturer to see if it's been treated with anti-moss compounds.  

Good growing!
Jacob Farin