pH Down lowers the pH of your nutrient solution into the range where roots can actually absorb what you have fed them. Most UK tap water sits around pH 7.5, and most feeds want 5.8-6.2 – so for anyone growing in coco or hydro this is not optional.
Why it matters more than another additive
Nutrient uptake is pH dependent. Outside the right band, elements are chemically present but locked out, and the plant shows a textbook deficiency while sitting in a full-strength feed. Adding more nutrient at that point makes it worse. Correcting pH is free by comparison.
Medium
Target pH
Hydroponics / rockwool
5.5 - 5.8
Coco
5.8 - 6.2
Soil
6.0 - 6.8
Using it safely
Always add nutrients first, then pH. Feed changes pH, so adjusting beforehand is wasted effort.
A little at a time. Concentrated pH Down moves a reservoir fast. Add a millilitre, stir, wait, measure.
Never neat onto roots, and never mixed directly with pH Up or silica concentrates.
Wear gloves. Professional strength is a strong acid.
Phosphoric acid is the standard and adds a small amount of phosphorus. Nitric acid versions are used where you do not want extra P late in flower.
You need a meter to use this at all – see pH and EC management. Also stocked: pH Up for correcting the other way.
Why buy pH Down from The Hydro Bros?
We are a hydroponics shop in Croydon and we know what the local tap water does to a feed. Discreet UK and European delivery, and excellent customer reviews on Trustpilot.
