Pioneering Hydroponics

Since 1976

Maintaining the perfect pH level

The perfect pH level changes depending on what you are growing in and of course what you are growing. We recommend a pH level between 5.8 and 6.5.

Check pH levels of your nutrient solution in your tank weekly. You can use an approved test kit e.g, Nutriculture liquid pH test kit or an easier and more precise result can be achieved by choosing a digital pH meter like the HM Digital PH-200 and PH-80

If the pH of the solution is in the correct range 5.8 – 6.5 you needn’t do a thing.

If the pH of the solution is above the correct range add phosphoric acid (pH Down).

If the pH is below the correct range add potassium hydroxide (pH Up).

Add a very small amount of phosphoric acid or potassium hydroxide to a glass of warm water and stir well before adding it to the nutrient solution. Once in the solution stir well again, or leave for 75 minutes before retesting pH.

pH Down or pH Up should be used very sparingly as it is easy to overdose with pH Down and pH Up. Overdosing would cause more damage to plants than for the solution not to be in the ideal pH range.

Safety First: Phosphoric acid is strongly acidic and potassium hydroxide is strongly alkaline. Always follow the safety instructions on the container. Never mix phosphoric acid with potasium hydroxide. You should never need both materials on the same site.

Good to know

Phosphoric acid and potassium hydroxide are very dense chemicals which do not mix readily with water. We advise to mix phosphoric acid or potassium hydroxide very sparingly to warm water stirring vigorously before adding it to the nutrient solution.

Take a note of the amount of phosphoric acid used to adjust your first tank of nutrient solution it will make it much easier when you need to do it again at solution changes. 

Avoid large changes in either pH or nutrient strength and do not let the solution level in your tank drop significantly.

Need help checking your pH levels? Take a look at our video below: