Description

General Hydroponics' 8 oz pH 4.01 Standard Reference Solution is specifically formulated for use with electronic pH meters and can be used with most pH, EC and TDS meters. Accurate to 0.01 at 77 degrees Fahrenheit, with General Hydroponics' pH 4.01 Standard Reference Solution you can feel confident your testing meter is reading accurately every time.

See product label for instructions on use.