pH Up is the generic name for alkaline products that raise the pH of a nutrient solution or water. The usual active ingredients are potassium hydroxide (KOH, strong and fast), potassium carbonate (K₂CO₃) or potassium bicarbonate (KHCO₃), which also add a little buffering. All of them add some potassium.
In practice
Most growers need pH Up less often than pH Down, because tap water and many fertiliser mixes tend to be alkaline or drift upwards. It is most common with RO water and acidic nutrient blends, or in coco and hydro when a new mix lands below about 5.5.
Add small amounts, stir or circulate for several minutes, and re-measure; RO water has little buffering, so a few drops can overshoot. Adjust after adding nutrients, never before. Dilute concentrated pH Up in water first for small reservoirs.
Safety: strong bases cause serious chemical burns to skin and eyes, often without immediate pain. Wear gloves and eye protection, store away from acids and out of reach of children and pets, and never mix pH Up and pH Down directly.
Don't confuse with
- Buffer additives: carbonate-based products raise both pH and alkalinity.
- Cal-Mag: raises calcium and magnesium; it does not reliably raise pH.
pH measures how acidic or alkaline a solution is on a 0–14 scale; in growing it controls nutrient uptake, with soil best near 6.0–7.0 and hydro 5.5–6.5.pH Down is any acid used to lower solution pH, commonly phosphoric, nitric or sulfuric acid; each adds a nutrient, and all need gloves and eye protection.Tap water is municipal or well water used for irrigation; its EC, alkalinity, hardness, sodium and disinfectant vary widely, so it should be tested before use.RO water is water stripped of most dissolved salts by reverse osmosis; it has near-zero EC and little buffering, so pH moves easily and Ca and Mg must be added.Coco coir is a growing medium made from processed coconut husk, prized for holding water and air at once; it binds calcium and magnesium unless buffered.Alkalinity is water's capacity to neutralise acid, mainly from dissolved bicarbonate and carbonate, reported in mg/L as CaCO3; it decides how much pH Down you need.Cal-Mag is a supplement supplying calcium and magnesium, usually as nitrates; need depends on cultivar, water source (RO vs tap) and medium (coco), not on LED lighting.pH drift is the gradual rise or fall of a nutrient solution's pH between adjustments, driven mainly by which ions the roots take up.
