pH Control Liquid & Tube

General Hydroponics® pH Test indicator and Vial. The General Hydroponics® pH Test Indicator can help you maintain an ideal pH level (which is between 5.5 and 6.5). This can be achieved by monitoring your pH using the super concentrated drops found with the test indicator. Based on the test results, pH Up or pH down can be added to adjust the pH as needed. The General Hydroponics pH Test Indicator works across a wide pH spectrum (pH 4.0 – 8.5).