TDS of water after fertilzer addition.

[Cheddarbob14]

I'm confident in knowing what I have as far as my solution (7.5 ml per gallon will result in 25 ppm). My questions are more in general, as I have various forms of potting mixes currently in use (semi hydro, bark, cedar/perlite combo), and a few varieties of orchids (do some fare better w more ppm). I just didn't want to start a new thread on the beginner page considering the main topic in here is dealing with tds's

[smokinjoe1952]

Using K-lite at 25 ppm N, as Ray suggested in this thread, what would the ~TDS be if using distilled or RO water?

[Ray]

Nobody knows....not even the manufacturer, but the EC should be about 0.17 mS.

Mix it correctly using mass to make a concentrate, let it down accurately, and measure it. That will be your answer.