TDS (Total Dissolved Solids) Meters

TDS are a measure of the amount of solids (mostly nutrient) in your solution. TDS, which is expressed in terms of PPM (or Parts per Million), is a good way to judge the overall concentration of the nutrient solution. If the TDS reading is too low, add more nutrient to increase the concentration. If the reading is too high, add pH-adjusted water to dilute the strength. Total Dissolved Solids must be measured using a digital meter. Calibration Solutions and batteries are featured below.

Milwaukee T75 Waterproof TDS Tester

Battery-powered test pen displays digital reading of a liquid's Total Dissolved Solids, expressed in parts per million. Waterproof. Includes protective case and replaceable electrode. 2-year warranty (1-year on probe).

• Milwaukee T75 Waterproof TDS Tester, $73.95

Milwaukee Constant TDS Monitor

Just place the remote electrode into your nutrient reservoir, then turn on the monitor for an instant--and constant--display of dissolved solids expressed as PPM. The sealed casing keeps moisture out, and the electrode is replaceable. 2-year warranty (1-year on probe).

• Milwaukee Constant TDS Monitor (9 volt battery powered), $104.99

Sunleaves Essential TDS Pen

This inexpensive pen is accurate to 2%, reliable for over 1,000 hours of continuous-use hours, and measures from 0 to 9990ppm. It features data-hold capability, auto shut-off and temperature compensation.

• Sunleaves Essential TDS Pen, $39.99

Bluelab Truncheon Meter

This unique product displays both TDS readings and EC readings through a series of flashing lights on the side of the meter. Hard to describe but easy to use, with excellent accuracy and no calibration required. Imported from New Zealand. Three year warranty.

• Bluelab Truncheon Meter, $149.95

EC (Electrical Conductivity) Meters

Electrical Conductivity is a measure of how much electrical current is able to pass through a nutrient solution. Mineral elements dissolved in a solution will conduct electricity, and EC meters measure this conductivity. EC readings can be used to judge the overall strength of a nutrient solution, similar to how you would use TDS readings from a TDS meter, but EC values are more widely used outside North America. If the EC reading is too low, add more nutrient to increase the concentration. If the reading is too high, add pH-adjusted water to dilute the strength. Electrical Conductivity must be measured using a digital meter or Truncheon meter.

Milwaukee Constant EC Monitor

Just place the remote electrode into your nutrient reservoir, then turn on the monitor for an instant--and constant--display of electrical conductivity expressed in mS/cm. The sealed casing keeps moisture out, and the electrode is replaceable. 9 volt battery operated. 2-year warranty (1-year on probe).

• Milwaukee Constant EC Monitor (9 volt battery powered), $104.99

Bluelab Truncheon Meter

This unique product displays both TDS readings and EC readings through a series of flashing lights on the side of the meter. Hard to describe but easy to use, with excellent accuracy and no calibration required. Imported from New Zealand. Three year warranty.

• Bluelab Truncheon Meter, $149.95

pH Testers & Meters

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 6.3. 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!

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, $6.95

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, $9.99
• Litmus Paper, 0-13 range, $9.99

Hanna Checker pH Tester

This affordable but reliable device features simple two point calibration and measures pH from 0.0 to 14.0, with a resolution of 0.01 and +/- 0.02 accuracy range. Unit includes replaceable electrode, batteries and instructions. Replacement electrode available. Tester and electrode protected by 6 month warranty.

• Hanna Checker pH Tester, $44.95

Oakton Waterproof pH Tester

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 pH Tester, $85.95

NutraDip Constant pH Monitor

Just place the remote electrode into your nutrient reservoir, then turn on the monitor for an instant--and constant--pH display. The sealed casing keeps moisture out, and the electrode is replaceable. Warranty 6 months electrode, 2 years monitor.

• NutraDip Constant pH Monitor (AC powered), $133.95

Miscellaneous Meters

Kill-A-Watt Monitor

Large LCD display will count consumption by the Killowatt-hour, same as your local utility. You can figure out your electrical expenses by the day, week, month or year. Check the quality of your power by monitoring Voltage, Line Frequency, and Power Factor.

• Kill-A-Watt Monitor, $39.95

Meter Calibration Solutions & Batteries

TDS Calibration Solution

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

• TDS Calibration Solution (1500 ppm), 8oz $8.20
• TDS Calibration Solution (1382 ppm), 20ml Packet $1.25

EC Calibration Solution

Use to calibrate your digital EC meter to 1413 uS.

• EC Calibration Solution (1413 uS), 20ml Packet $1.25

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), 8oz, $6.95
• pH Calibration Solution (pH 7.0), 8oz, $6.95
• pH Calibration Solution (pH 4.0), 20ml Packet $1.25
• pH Calibration Solution (pH 7.0), 20ml Packet $1.25

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), $15.00

Batteries for Digital Pens

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

• Batteries for Digital Pens (4), $4.95

Light Meters

Hydrofarm Digital Light Meter

Displays exact footcandle readings in digital display. Adjust meter according to light source (fluorescent, HID, sunlight, etc.) for accurate readings.

• Hydrofarm Digital Light Meter, $44.95

Temperature & Humidity Meters

Aquarium Thermometer

Accurately displays temperature of water or solutions.

• Aquarium Thermometer, $2.99

Temperature/Humidity Indicator

This dual-gauge readout displays current temperature and relative humidity level.

• Temperature/Humidity Indicator, $8.95

Active Air Digital Thermometer/Hygrometer

Displays current temperature and humidty levels, and includes a remote probe for second zone temperature. Records high and low points for both temperature and humidity.

• Active Air Digital Thermometer/Hygrometer, $19.95

Soil Meters & Testers

Control Wizard Soil pH and Moisture Meter

This soil pH and moisture meter is not only extremely accurate, but is much cheaper than other products on the market with comparable accuracy. Just clean the electrodes, put into the soil and the pH reading is automatically displayed.

• Control Wizard Soil pH and Moisture Meter, $59.95

Active Air Three-Way Meter

Insert probes into soil to measure soil moisture and pH. Also includes a basic light meter.

• Soil pH, Light, & Moisture Three-Way Meter, $9.95

Soil pH Test Kit

Take a small soil sample, mix with water and test solution, and a color change indicates pH. Good for 10 tests.

• Soil pH Test Kit, $7.95

Deluxe Soil Test Kit

Similar to above, but provides tests for pH as well as the amount of nitrogen, phosphorous, and potassium in the soil. 10 tests each.

• Deluxe Soil Test Kit, $18.99