pH Up raises the pH of a nutrient solution. It is needed far less often than pH Down – most UK tap water is alkaline to begin with – but there are three situations where you will not get far without it.
When you need it
RO or heavily filtered water. Reverse osmosis strips the buffering minerals, so the resulting solution is unstable and often drifts low once feed is added.
Overshooting with pH Down. Concentrated acid moves a reservoir quickly. Everyone overshoots eventually.
Naturally acidic inputs. Some organic feeds, and rainwater collection, land well below target.
Using it
Most pH Up is potassium hydroxide, which adds a small amount of potassium along with the correction – worth knowing if you are already running a heavy PK booster. Add nutrients to the water first, then adjust, a millilitre at a time with a stir and a pause between doses. Never mix it directly with pH Down or with silica concentrate.
Target ranges
5.5-5.8 for hydroponics and rockwool, 5.8-6.2 for coco, 6.0-6.8 for soil. In organic soil you rarely need to adjust at all – a living soil buffers itself, and chasing pH usually does more harm than leaving it alone.
We are a hydroponics shop in Croydon and we can tell you whether your water actually needs it. Discreet UK and European delivery, and excellent customer reviews on Trustpilot.
