Hi i have a simple question i need answered

This is my first time out on hydro (i have only done soil before), i brought a truncheon to measure my nutrient levels and i was wondering why it was showing a reading in plain water, do i have to minus this reading after i have added my nutrients from the reading then. I take it that the truncheon is reading the impurities in my tap water. (i know its a simple question but i cannot find an answer), thanks ....
Ryder Reviewed by Ryder on . Nutrient levels Hi i have a simple question i need answered :confused: This is my first time out on hydro (i have only done soil before), i brought a truncheon to measure my nutrient levels and i was wondering why it was showing a reading in plain water, do i have to minus this reading after i have added my nutrients from the reading then. I take it that the truncheon is reading the impurities in my tap water. (i know its a simple question but i cannot find an answer), thanks .... Rating: 5