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What Is pH, Why Do I Have to Worry About It, and How do I Maintain It?

ph-test-indicatorpH stands for “Potential of Hydrogen” and is the symbol for the hydrogen ion (H+) in liquids. pH has a range from 0 (acidic) – 7 (neutral) – 14 (alkaline).

For hydroponics, we are aiming for a pH between 5.5 to 6.2 (slightly acidic); this is suitable for most hydroponic crops. For soil, we recommend a pH between 6.5- 6.8. Ensuring that the pH remains within this range will help maintain good plant health. Keeping the pH in this range ensures that nutrients are readily available to the plant. Once the grower goes above or below this optimal range certain nutrients start becoming unavailable to the plant.  pH is maintained by adding either pH Up or pH Down.

What is pH Up and Down?

Up is potassium hydroxide and pH Down is phosphoric acid (commercial growers will sometimes also use Nitric acid and Sulfuric acid). Customers who use tap water will normally need to use pH down to balance the pH of their nutrient solution. Tap water tends to have a lot of carbonates which tends to buffer tap water at a higher pH. Customers who use RO water will need to use pH Up as the reverse osmosis strips the tap water of all the carbonates, thus leaving the water with no buffering ability. The nutrients the growers use to feed their plants is acidic, and once the grower has applied all the required nutrients and enhancers the reservoir pH can be below 5. This is too low for plants; thus pH Up needs to be used in order to raise the pH to at least 6. Customers using both pH Up and Down should take care when using these products as both are very concentrated. Only small amounts should be used at a time until the customer becomes familiar with the products.

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