pH Up & pH Down are tank controllers that assist in reaching the desired pH level. The pH scale measures how acidic or basic (alkaline) a substance is. It ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic (alkaline). Plants thrive in a pH range of 5.7-6.2. When preparing nutrients, or regularly monitoring your reservoir or tank, you should always check your pH levels to ensure that the pH stays within an acceptable range for your plants. When pH levels become too high, nutrients become non-bioavailable, a phenomenon commonly referred to as ‘nutrient lockout’. Accordingly, pH control using pH Up & pH Down is essential to ensure that nutrients remain readily available for plant growth.