pH Testers & Supplies
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IG 101

Water & Food


Checking the pH in your hydroponic solution is a key element of successful gardening! Most plants do well in a slightly acidic solution, so try to maintain an average pH of 6.0. If your pH is too high (alkaline), add pH DOWN to lower the pH. If pH is too low (acidic), add pH UP to adjust the water. Check pH—and adjust if necessary—every 1-2 days! (All products on this page are for checking and adjusting pH of water or nutrient solutions. Click here for Soil pH Testers).

pH Meters & Testers

pH Control Kit

Contains 8 oz Ph Up (add a little at a time when your nutrient pH is too low in order to raise the pH to the proper level), 8 oz Ph Down (uses food grade Phosphoric acid to lower the pH to the proper level), and Ph Test Indicator (fill a test-tube halfway with nutrient, add a few drops of pH Test Indicator, and observe the coloration of the liquid in the test vial. Use 3 drops per 5mL of solution).

  • pH Control Kit
pH Test Kit

Tests the pH of water or nutrient solution--add 3 drops of test fluid to water sample, then compare to a color chart. Each kit yields about 100 tests.

  • pH Test Kit
Litmus Paper

Litmus paper test just like you used in science class! Tear off a 2" strip then dip into nutrient solution. A vivid color change indicates pH.

  • Litmus Paper, 5.5 to 8.0 range
  • Litmus Paper, 0-13 range
Oakton Waterproof Digital pH Pen

Battery-powered test pen displays digital reading of a liquid's pH, expressed in 0.1 increments from 0 to 14. Waterproof. Includes protective case and replaceable electrode. 2-year warranty (1-year on probe).

  • Oakton Waterproof Digital pH Pen
Bluelab pH Pen

The highest quality pen on the market.

  • Bluelab pH Pen

pH Adjusters

Liquid pH Down

AHL pH down is a 9% Phosphoric Acid solution which lowers the pH of water or nutrient solution. Usage amount depends on level of adjustment...usually 1/8 to 1/4 teaspoon per gallon. (Caution: Keep out of reach of children!)

  • pH Down 16 oz (pint)
  • pH Down 32 oz (quart)
  • pH Down 128 oz (gallon)
Dry pH Down

Citric acid is a dry powder used to lower pH of water or nutrient solution. Citric acid will not be as pH stable as phosphoric acid, but citric acid is recommended for use in soil gardens or organic hydroponics. Use just a pinch per gallon.

  • Citric Acid, 1 lb.
  • Citric Acid, 5 lb.

Earth Juice Natural down is a dry granular citric acid.

  • Earth Juice Natural Down 2lb,
  • General Hydroponics Dry pH Down 1.5 lb,
Liquid ph Up

A 9% Potassium Hydroxide solution. Raises pH of water of nutrient solution. Amount used depends on level of adjustment...usually 1/8 to 1/4 teaspoon per gallon. (Caution: Keep out of reach of children!)

  • Technaflora pH Up 32 oz (quart),
  • General Hydroponics pH Down Gal,
Dry pH up
  • Dolomite Lime 4lbs,
  • Earth Juice Natural pH Up, 2 lbs,
  • General Hydroponics Dry pH Up 1.5 lb,

Meter Calibration Solutions & Batteries

pH Calibration Solution

Use to calibrate your digital pH meter. Most meters can calibrate at both points, or for a single calibration choose the setpoint closest to your average solution pH.

  • pH Calibration Solution (pH 4.0), 8 oz,
  • pH Calibration Solution (pH 4.0), single use packet,
  • pH Calibration Solution (pH 7.0), 8 oz,
  • pH Calibration Solution (pH 7.0), single use packet,
Electrode Cleaning Solution

Dip electrode in Part A for 5 minutes, then Part B for 5 minutes, then rinse again in Part A. Increases accuracy and prolongs electrode life! Sold as a set of Part A & Part B.

  • Electrode Cleaning Solution Part A (8 oz) & Part B (8 oz)
Batteries for Digital Pens

Replacement batteries for pH, TDS or EC pens. Pack of 4.

  • Batteries for Digital Pens (4)



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