Expert: Sarracenia Northwest - 4/5/2011

Question
My water supply tests out at Ph 7.8 and nitrate at 10 ppm.  What does this mean for a plastic lined in-ground CP bog with a volume of around 200 gallons?

Answer
With a high pH, it means that you have lots of minerals in your water.  Without minerals, water is just under 7.0.  I don't use pH, however, as a way to determine mineral levels.  I prefer total dissolved solutes, or TDS, which is measured in parts per million.  Water is generally safe to use on carnivorous plants if the TDS is less than 50 ppm.  Since your water is alkaline, it's likely you have lots of calcium and/or magnesium.  To get a more accurate reading, you should consider checking TDS.  You can find simple test kits at most aquarium supply stores.  

You should consider using a reverse osmosis unit to filter out these minerals as part of your investment for your in-ground bog garden..  It will also filter out the nitrates, though your levels are nothing to be concerned about.  In the short term, your plants will be OK, but not in the long-term (several months of using this type of unfiltered water). Depending on your climate, you may need to get a unit that will process up to 350 gallons per day (GPD), which is about 14.5 gallons per hour.  Most inexpensive home units usually process only 50 GPD or about 2 gallons per hour.  In the height of summer, this might not be adequate and will make watering your bog garden painfully slow.  At the very least, you may need to a unit that can handle 150 GPD.  This will definitely make watering a lot easier when the temperature is soaring.

Good growing!
Jacob Farin