The ideal pH for almost all hydroponic applications is 6 (5.8 - 6.2). Acid Neutral Alkali 1 2 3 4 5.8 6.2 7 8 9 10 11 12 13 14 Acid Neutral Alkali 1 2 3 4 5 6 7 8 9 10 11 12 13 14 What pH for a passive hydroponic system? These are simple top watered pots or a gravity fed system, such as Autopot. These systems use pots full of a medium such as Soil, Perlite, Rockwool (grow cubes or granulate) or Coco. It is ideal to make a 200 litre batch of nutrient at a time. Once this is made up to the correct ‘strength’ (conductivity), the pH can be checked and adjusted to the ideal level of 5.8-6.2. A careful note should be made of the exact amount of pH UP or pH DOWN that is added at this time, so as to develop a reliable routine of good plant management. What pH for an active hydroponic system? These are pump powered systems, such as NFT, ebb and flow, drippers, DWC, IWS and aeroponics. In an active system the pH will need checking and adjusting in the main tank on a regular basis. In most systems fresh water is added to the tank to replace that used by the plants. The incoming water is usually of a higher pH than the nutrient solution so there tends to be an upward drift in pH. This can be corrected by the addition of small amounts of pH DOWN. This process of pH control can be carried out with a pH kit but as it needs doing often in this system, the busy grower would be better off using a meter. Growth Technology – The Grower's Guide | 17 BLOOM How to use: pH pH is a measurement of the acidity or alkalinity of a solution. On a scale of 0-14 neutrality is represented as 7. pH is important because nutrients only become available to the plants within a specific pH range. pH solutions are very concentrated, so always dilute in water before use. Add a little at a time, allowing it to mix, then check the pH. Repeat as necessary. Ideally waiting 30 minutes before final adjustment.
The Growers Guide
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