Active systems are ones in which the nutrient solution is supplied to the plants by pumping, such as Ebb and Flow tables or NFT systems. In most domestic systems, the solution is re-circulated to the roots continuously over a period of time. 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 regular 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, the busy grower will be better off using a meter. If the water supply is classified as hard, the grower must be very careful with re-circulating systems.
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 regular 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, the busy grower will be better off using a meter. If the water supply is classified as hard, the grower must be very careful with re-circulating systems.
