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A TDS tester is critical when growing plants by hydroponics.

Hydroponic gardeners all over the world monitor nutrient levels in roughly the same way—by measuring total dissolved solids in the growing solution — but they have different preferences for the format of their test results. Growers in the U.S. often examine a simple ratio known as parts per million PPM). High concentrations of salts increase the solution’s electrical conductivity (EC).

Total dissolved solids readings help to indicate the density of solution which can help to determine when it’s time to add nutrients. Temperature can affect TDS/EC meter readings. It is important that you read your hydroponics nutrient packaging carefully to make sure feeding indications correspond with your meter.

Hydroponics TDS/EC Meter (aka nutrient or "ppm" meter):

COM-100: Waterproof EC/TDS/Temp Meter





Hydroponics pH Meter:

PH-200: Waterproof pH Meter







Information below provided by Sunleaves.


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For great results, consult the ppm table below for assorted fruits, veggies, herbs and tropicals. Keeping your nutrient solution at the right concentration is important for maintaining optimum growth!  (TDS level ranges below are listed in ppm.)

Species TDS Range   Species TDS Range
African Violets 840-1050   Ficus 1120-1680
Artichoke 560-1260        Garlic 980-1260
Asparagus 980-1260   Gladiolus 1400-1680
Aster 1260-1680   Impatiens 1260-1400
Bananas 1260-1540   Lavender 700-980
Basil 700-1120   Leek 980-1260
Beans 1400-2800   Lettuce 560-840
Blueberries 1260-1400   Mint 1400-1680
Broccoli 1960-2450   Okra 1400-1680
Cabbage 1750-2100   Palms 1120-1400
Carnation 1260-2450   Parsley 560-1260
Carrots 1120-1400   Peas 980-1260
Cauliflower 1050-1400   Rosemary 700-1120
Celery 1260-1680   Sage 700-1120
Chives 1260-1540   Spinach 1260-1610
Cucumber 1190-1750   Strawberries 1260-1540
Eggplant 1750-2450   Thyme 560-1120
Endive 1400-1680   Tomatoes 1400-3500
Ferns 1120-1400   Zucchini 1260-1680



Useful Information:


Click here to read an article about Calibrating and Caring for Your pH Meter, from the July 2010 issue of Urban Garden Magazine.  The article was written by Rob Samborn, Director of Sales & Marketing for HM Digital.

Click here to read an article about TDS and EC Meters for Hydroponics Explained, from the June 2010 issue of Maximum Yield Magazine.  The article was written by Rob Samborn, Director of Sales & Marketing for HM Digital.













Education Center

Our Education Center is your resource for all things water.  This knowledge base includes numerous articles on water, water quality and water filtration.

Did You Know?

Different government agencies have different requirements for water quality.  For example:

  • The U.S. EPA sets the maximum contaminant level for TDS at 500 ppm.
  • The World Health Organization (WHO) sets the maximum contaminant level for TDS at 1000 ppm.