Question
I know nepenthes can take somewhat harder then most other carnivorous plants. I was wondering how many PPM is ok.

Answer
Hi Jason,

There's no clear cut answer on this one since a lot of it depends on species.  In general, lowland species are much more tolerant of hard water than highland species.  The ultra highlanders should be given mostly mineral-free water.

Most Nepenthes commonly found in cultivation are tolerant of water with 100-200 ppm of dissolved solutes.  However, you should always make sure the water drains completely through the pot.  

The main thing to watch for is a decrease in pitcher production.  If pitchers are smaller and fewer in numbers despite giving your plant the proper lighting, then change the soil to remove the excess minerals.  You'll also need to water mineral-free water until pitchers resume.

Other than that, that would probably be the only indication your plant is reacting to the minerals, and it may take several months to a year for it to show up depending on how hard your water is.

Good growing!
Jacob Farin