General Hydroponics: PPM Calibration Solution Size:1 Quart The Bluelab pH Pen also

The Bluelab pH Pen also measures the temperature of the solution

nutrient deficiencies

Simply plug it in and you’re ready to grow

And many others give out different levels of quality

but other companies may claim to have “organic” products

General Hydroponics: PPM Calibration Solution Size:1 Quart The Bluelab pH Pen alsoGeneral hydroponics uses the highest quality electronic meter reference solutions. Growers can use our reference solutions widely among many popular brands of meters using the NaCl scale. General hydroponics technicians check each batch to ensure that our solutions are exactly calibrated each time they are used.