Growth Technology pH Down – 30% or 81% Phosphoric Acid
Growth Technology pH Down – 30% or 81% Phosphoric Acid
Growth Technology pH Down – Because Nutrients Only Work at the Right pH
You can give a plant the finest feed money can buy and still watch it go hungry. If the water's pH is wrong, nutrients lock up in forms roots simply can't absorb: iron, calcium, magnesium and phosphorus are first to go. Most UK tap water comes out of the tap too alkaline for plants to feed at their best, and in hydroponics, coco and semi-hydro the pH tends to keep rising day by day. pH Down brings it back into the zone where every nutrient is available.
Growth Technology pH Down is made from phosphoric acid, one of the most stable and widely used pH adjusters in horticulture. It's a little nutrient as well as an adjuster, since phosphorus is something plants use.
30% or 81%?
| Strength | Best for |
|---|---|
| pH Down 30% | Gentler and easier to control: ideal for small reservoirs, watering cans, semi-hydro and houseplants, or anyone new to adjusting pH |
| pH Down 81% | Highly concentrated: best value for bigger tanks and experienced growers, as a few drops go a long way |
Both are phosphoric acid. The 81% is simply far stronger, so start with tiny amounts.
Target pH
- Hydroponics and semi-hydro (LECA, pon): 5.5–6.2
- Coco coir: 5.8–6.2
- Soil and compost: 6.0–6.5
How to Use
- Mix all your nutrients and additives into the water first.
- Stir, then measure the pH with a meter or test kit.
- Add pH Down a few drops at a time (use a syringe), stir well and re-test.
- Repeat until you reach your target. Recirculating systems may need checking daily, as pH drifts upwards.
Growth Technology recommend that if you dilute pH Down 30%, a 1 in 10 dilution is ideal (500ml in 5 litres).
⚠️ Safety
DANGER – causes severe skin burns and eye damage. Both strengths are corrosive phosphoric acid. Wear gloves and eye protection, keep out of reach of children, and never mix pH Down with pH Up, or with any concentrated nutrient. Store acids and alkalis separately. A safety data sheet is available from Growth Technology.
🌿 Rose's Pro-Tip: always adjust pH last. Every product you add changes the pH, so measuring before everything is in is wasted effort. And use a syringe, not the cap: with 81% especially, the difference between "perfect" and "overshot" is a couple of drops.
Sizes
30% and 81% in 250ml, 1 Litre and 5 Litres, plus a measuring syringe.
Black Flag Horticulture Ltd, Coventry – genuine Growth Technology stockists.