m0useanswered grow question 3 years ago If the meter is flashing x10, multiply the number by 10.
so 166x10 = 1,660ppm
that's quite high, for most plants. depends on where you are in your grow. More information is needed.
You want to be measuring your TDS in 1L then multiplying that ratio for how large your reservoir is.
If that cup is a solution you prepared from the main tank, then it might be to high.
If the entirety of the teaspoon/nutrients are in that little cup, that might be why the reading is so high.
Over all need more information to know if its to much or little. But I'm guessing its to much,
Best Of Luck and Happy Growing