Acid Tubing (White) Suitable for Bluelab PeriPod M and Bluelab pH Controller Wi-Fi - 4mAcid Tubing (White) Suitable for Bluelab PeriPod M3, PeriPod M4 and Bluelab pH Controller Wi Fi 4meters. Includes joiners (2x 1 8 straight, PVDF) As a guide, Bluelab recommends the following maximum concentration for commonly used acids and alkalines: Nitric Acid = < 35% Phosphoric Acid = < 85% Citric Acid = < 60% Potassium Hydroxide = <60% Potassium Silicate = <60% The chemical concentrations stated above are a guide. Variations in temperature,