As a guide Bluelab recommends the following maximum concentration for commonly used acids and alkalines;            

Nutrient tubing (LDPE)
Nitric Acid <10%, Phosphoric Acid <40%, Sulfuric Acid <50%, Citric Acid <10%, Potassium Hydroxide Concentrated, Potassium Carbonate Concentrated, Potassium Silicate Concentrated.

The chemical concentrations stated above are a guide. Variations in temperature, pressure, or UV exposure may cause tubing failure which could lead to serious injury if proper safety precautions are not followed. For this reason, it is recommended that the tubing be tested with the desired chemical in the specific application to determine suitability. No warranty (neither express or implied) is given that the information in these tables is accurate or complete or that any material is suitable for any purpose.