pH and nutrient control

Get the water right first.

Nothing in the tank is available to a plant if the pH is wrong. This is the pH up and down, the calcium and magnesium that soft water leaves you short of, and the meters and buffers that tell you where you are.

Nothing matches all of those filters.

pH up, pH down and conditioners

Moving the tank into range, and holding it there once it is.

Growth Technology PH Down 81% – Phosphoric Acid pH Reducer

£4.49

Growth Technology pH Up – Potassium Hydroxide pH Adjuster

£3.49

SoilCocoHydro

Ecothrive Neutralise – Water Conditioner and Dechlorinator

£4.99

BioBizz Bio pH- Organic pH Down – For Soil, Coco & Hydro

£4.30 £6.00

Growth Technology pH Down 30% – Phosphoric Acid Adjuster

£10.45

Veg+Bloom PHLO – pH Down & Water Conditioner

£22.49

BioBizz Bio pH+ Organic pH Up – For Soil, Coco & Hydro

£4.49

Dutch Pro pH Up – Hydroponic pH Control

£8.95

Plagron Lemon Kick – Organic Citric Acid pH Down

£7.49

SoilCocoHydro

Hydrotops Flush – Root Zone Salt Build-Up Cleaner

£19.00

SoilCocoHydro

Athena Balance Blended Line – pH Stabiliser

£16.49

Cal-Mag and calcium supplements

What soft water and reverse osmosis water leave out.

SoilCocoHydro

Green Planet Pro-Cal – Calcium Magnesium Iron Supplement

£11.49

SoilCocoHydro

Canna Cal-Mag Agent – Calcium & Magnesium for RO Water

£12.49

SoilCocoHydro

Essentials PLUS CalMag – Cal Mag for Plants

£65.95

SoilCocoHydro

British Minerals CalMag – Calcium & Magnesium Supplement

£14.90

SoilCocoHydro

RAW Calcium Magnesium – Water-Soluble Cal-Mag Supplement

£12.58

SoilCocoHydro

Hesi CalMag – Calcium Magnesium Supplement for RO Water

£14.49

SoilCocoHydro

Terra Aquatica CalMag – Calcium Magnesium for RO Water

£7.99

SoilCocoHydro

Athena CaMG Blended Line – Cal-Mag Supplement

£16.49

CocoHydro

BioGreen Calgel – Calcium Supplement for Coco & Hydro

£31.95

SoilCocoHydro

Mills CalMag – Calcium & Magnesium Supplement

£104.99

SoilCocoHydro

Dutch Pro CalMag – Calcium & Magnesium Supplement

£19.45

Meters, dosers and controllers

Reading pH and EC, and in the case of the controllers, correcting them for you.

pH Test Kit – Drop Test Reagent for Nutrient Solution

  • Brand Hydro Crop Shop
  • Type Meters
  • Price from £4.95
  • Availability In stock
£4.95

Out of stock

VIVOSUN pH and TDS Meter Combo – Hydroponic Water Test Kit

  • pH range 0.00–14.00, ±0.1 pH
  • TDS range 0–9999 ppm, 1 ppm resolution, ±5%
  • EC range 0–9999 µS/cm, 1 µS/cm resolution, ±5%
  • Temperature 0.1–80°C (32–176°F), 0.1° resolution
£29.49

Milwaukee EC40 Nutrient Truncheon – EC Meter for Hydroponics

  • Model Milwaukee EC40 EC/TDS Nutrient Meter
  • Range 0.2 to 4.0 mS/cm | 2 to 40 CF | 100 to 2000 ppm (...
  • Resolution 0.1 mS/cm (70 ppm on the 700 scale, 50 ppm on the...
  • Accuracy ±4% of reading ±1 resolution point
£79.90

Essentials EC Meter – Nutrient Meter for Hydroponics

  • Range 0.1 – 10.0 mS
  • Resolution 0.1 mS
  • Accuracy ±2% full scale
  • Temperature compensation automatic, 0°C – 70°C
£54.95

Bluelab External Lockout and Alarm Box – Float Switch Alarm

  • Brand Bluelab
  • Model External Lockout and Alarm Box (PROEXBOX)
  • Compatible with Bluelab Pro Controller and Pro Controller Wi-Fi
  • Inputs external lockout switches, normally open or norma...
£57.70

Bluelab PeriPod L3 – Nutrient Doser for Hydroponics

  • Brand Bluelab
  • Model PeriPod L3 (PERIPODL3)
  • Pumps 3 peristaltic pumps
  • Flow rate up to 1200ml/min per pump, accuracy ±10% at 25°C
£2,595.30

Bluelab 2.77 EC Standard Solution Box of 6 – EC Calibration

  • Brand Bluelab
  • Conductivity 2.77 EC / 27.7 CF at 25 °C
  • ppm equivalents 1385 ppm (500 scale) / 1940 ppm (700 scale)
  • Use accuracy checks and calibration of EC, CF and ppm...
£51.95

Milwaukee Smart Combi Meter – pH & EC Meter Hydroponics

  • pH meter range 0.0-14.0 pH
  • EC meter range 0.0-10.0 mS/cm
£207.95

Bluelab pH 4.0 Solution Sachets – For pH Meter Calibration

  • Contents 30 sachets
  • Volume per sachet 18ml
  • Solution pH 4.0 calibration buffer
  • Format single-use, tear-open pouch
£39.95

Bluelab pH 7.0 Solution Sachets – For pH Meter Calibration

  • Contents 30 sachets
  • Volume per sachet 18ml
  • Solution pH 7.0 calibration buffer
  • Format single-use, tear-open pouch
£39.95

Bluelab 2.77 EC Solution Sachets – For EC Meter Calibration

  • Contents 30 sachets
  • Volume per sachet 18ml
  • Solution 2.77 mS/cm EC conductivity standard
  • Format single-use, tear-open pouch
£39.95

Bluelab pH Controller – Automatic Dosing for Reservoirs

  • Control range 0.1-13.9 pH, resolution 0.1
  • Dose rate 10ml per minute
  • Reservoir capacity up to 760 litres
  • Dimensions 20 x 11 x 21cm
£594.99

Bluelab pH Controller Wi-Fi – Remote Dosing via Edenic App

  • pH range 0.0-14.0, resolution 0.1, accuracy +/-0.1
  • Pump flow rate up to 120ml/min, variable speed
  • Connectivity optional Wi-Fi, Edenic app
  • Power 100-240VAC, 50/60Hz, 5VDC 1.5A output
£514.95

Milwaukee pH51 Waterproof pH Meter – For Nutrient Solutions

  • Type Handheld digital pH meter
  • Range 0.0 to 14.0 pH
  • Accuracy ±0.1 pH
  • Calibration Manual, 1 or 2 point, via trimmers
£41.49

Bluelab Pro Controller Wi-Fi – pH & EC Automation

  • Brand Bluelab
  • Measures pH, conductivity and temperature
  • Monitoring Continuous, 24/7
  • Connectivity Built-in Wi-Fi, integrates with Edenic.io, can be...
£1,170.95

Essentials pH Meter – Hydroponic Nutrient Solution Tester

  • Range 0.0 to 14.0 pH
  • Resolution 0.1 pH
  • Accuracy +/- 0.2 pH
  • Battery 4 x 1.5 V button cell
£44.49

Bluelab PeriPod M3 – Automatic Nutrient Doser

  • pH dosing pump 1x peristaltic, 120ml/min (4fl oz/min)
  • Nutrient dosing pumps 2x peristaltic, 120ml/min (4fl oz/min)
  • pH tubing 4 metres (13ft) acid/alkaline resistant food-grade
  • Nutrient tubing 3x 4 metres (13ft) food-grade
£873.95

Water Conditioning Toolkit – pH & EC Control Kit

  • EC meter Bluelab Truncheon Nutrient Meter V2
  • pH testing Aqualine pH Stick
  • pH adjustment Growth Technology pH Up and pH Down
  • Water treatment Ecothrive Neutralise (chlorine and chloramine)
£178.99

Probe care and calibration

Buffer solutions, storage fluid and cleaner. A probe reads wrong long before it reads nothing.

Essentials LAB Buffer pH – Meter Calibration Solution

£3.90

Growth Technology pH Buffer 4 – Calibration Solution

£2.95

Growth Technology pH Buffer 7 – Calibration Solution

£2.95

Single elements and trace

One element at a time, for correcting a shortage without lifting the whole feed.

SoilCocoHydro

Canna Phosphorus (P 20%) Mono – Single-Element Bloom Feed

£9.99

SoilCocoHydro

Growth Technology Liquid Silicon – Silica Plant Supplement

£3.49

Organic

Canna Potassium (K 20%) Mono – Chloride-Free Organic Feed

£12.49

SoilCocoHydro

Canna Nitrogen (N 17%) Mono – Liquid Vegetative Feed

£9.99

SoilCocoHydro

Terra Aquatica Oligo Spectrum – Trace Element Supplement

£5.99

SoilCocoHydro

Canna Mono Trace Mix – Micronutrient Fertiliser

£9.99

SoilCocoHydro

Canna Iron (Fe) Plus Mono – Chelated pH-Stable Feed

£9.99

SoilCocoHydro

Canna Calcium (Ca 15%) Mono – Chloride-Free Liquid Feed

£9.99

The full range

Black Nitrile Gloves – Latex-Free Powder-Free Disposable

£12.49

SoilCocoHydro

Grotek Cal-Max – Calcium Magnesium Iron Supplement

£12.95

SoilCocoHydro

RAW Phosphorus – 9-61-0 Straight Element Corrective

£9.95

SoilCocoHydro

RAW Potassium – Water-Soluble Straight Element Corrective

£9.88

SoilCocoHydro

RAW Nitrogen – 20-0-0 Straight Element Corrective

£9.88

Organic

Advanced Nutrients OG Organics Sensi Cal Mag Xtra

£25.45

SoilCocoHydro

Advanced Nutrients Sensi Cal Mag Xtra – Chelated Iron

£10.49

pH up, pH down and calibration for grow tents

Nutrients only become available to the plant within a fairly narrow pH window, so a feed that's perfectly mixed but sitting outside range is close to wasted. Coco and hydro growers should be aiming for pH 5.8 to 6.2 at the root zone; soil is more forgiving at 6.0 to 6.5. Check pH after mixing nutrients, not before — adding concentrate always shifts the reading, sometimes by half a point or more.

Canna pH Down is a bloom-specific acid concentrate that plays nicely with Canna's own base feeds; most pH down products work fine across brands as long as you dose gradually. Meters drift over time, which is why Growth Technology Buffer 4 and Buffer 7 calibration solutions matter — recalibrate a digital pH pen roughly every two to four weeks, or immediately if readings start looking off compared to a fresh mix.

What's on the shelf

  • Growth Technology — Buffer 4 and Buffer 7 calibration fluid, plus Liquid Silicon for buffering pH swings at the root.
  • GHE — Flora Kleen, a reservoir and root-zone cleaner that also helps correct pH drift caused by salt build-up.
  • Canna and Ecothrive — pH Down (bloom), Cal-Mag Agent for hard water, and Neutralise for stripping chlorine and chloramine from mains water before it hits the reservoir.

If you're topping up a hydro reservoir daily, water can drift half a point or more overnight as roots take up nutrient unevenly — check first thing each morning rather than trusting yesterday's reading. Pair a meter from meters with your calibration fluid, and see base feeds for the nutrients you're actually correcting pH for.

Express Delivery available, free over £60. Ring the shop on 020 3488 0419 for advice, six days a week.