Growth Technology pH Down 30% Phosphoric Acid lowers the pH of nutrient solutions, often in the flowering stage. It is a very acidic solution and should be handled with caution.

Please click here to download the safety data sheet.

Why is it important to adjust pH with Growth Technology pH Down?

pH is the measure of acidity or alkalinity of an aqueous solution. If a solution is acidic then it has a pH in the range of 0 to 6.9. If a solution is alkaline then it has a pH in the range of 7.1 to 14. Pure water or deionised water is neutral at pH 7.0. The ideal pH for most hydroponic gardening applications is between 5.8 and 6.2, except for Rockwool cultivation, which likes a slightly lower pH of about 5.5.

Passive Hydroponics

Passive hydroponic systems consist of growing in containers or pots filled with a medium, e.g. soil, coco, perlite, vermiculite, rockwool cubes, or hand-watering rockwool slabs. Usually for this type of cultivation we would recommend that the grower makes up one large container of nutrient at a time. A 200 litre plastic drum is an ideal container.

Once the grower has made up the correct ‘strength’ (conductivity), they can check and adjust the pH to the ideal level of 5.8-6.2. The grower should make a careful note of the exact amount of pH UP or pH DOWN they add at this time. In the future, add this amount as a routine when making up solutions. The pH should remain pretty constant from batch to batch, although the grower should conduct spot checks from time to time. Ideally using a meter. The nutrient solution in the tank should remain stable and can be applied to plants as needed.

Active Hydroponics

Active hydroponic systems supply the nutrient solution to the plants by a pump system. These systems include NFT, Flood & Drain, Aeroponics, and DWC Systems. Most systems re-circulate the nutrient solution to the roots continually over a period of time.

In an active system the grower checks and adjusts the pH in the main tank on a regular basis. In most systems, they add freshwater 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. Correct this by the regular addition of small amounts of Growth Technology pH Down. The grower can carry out this process of pH control with a pH test kit. But as it needs doing often in this system, the busy grower would be better off using a meter.