Water hardness °dH

  • Nutrient solution: The simplest Solution

    Here is a recipe for small systems that supply tomatoes, peppers and leafy vegetables:
     
    Ingredients
    Base with micronutrients/trace elements: Masterblend 4-18-38 Hydroponic Fertilizer: this is still missing magnesium sulfate and calcium nitrate.
    One kilo costs about 30 to 49 euros and is enough for about 1500 liters of nutrient solution
     
    Magnesium sulfate: Epsom Salt
    One kilo costs about 5 euros 
     
    Calcium nitrate: PowerGrow Calzium Nitrate 15.5-0-0
    One kilo costs about 24 euros 
    Recipe
    Mix the ingredients in the following ratios: (2:1:3). You must not mix all the ingredients together .
    To do this, take two containers (bottles) of 500 ml each. This will prevent the calcium nitrate from reacting with the phosphate and precipitating.
     
    Fill the first bottle with 120 grams of NPK fertilizer and 60 grams of magnesium sulfate. If you use warm water (preferably deionized or distilled), the components dissolve better. Remember that tap water already contains calcium and magnesium. Depending on the water hardness, you should reduce the amount of calcium and magnesium. One °dH corresponds to 10 mg CaO (calcium oxide) per liter of water.
     
    Contents  division
     120 grams of Masterblend 4-18-38 (about 1/2 cup and a tablespoon) 
     60 grams of magnesium sulfate (about 4 tablespoons)
    		  Solution 1: mix with 500 ml water
     180 grams of calcium nitrate (about 3/4 cup)  Solution 2: mix with 500 ml water
     
     
    Use / Concentration
     Plant  concentration 
     Fruit-bearing bedding plants
     Solution 1: 3 ml per liter of water: for 10 liters take 30 ml, for 1 gallon = 12 ml
     Solution 2: 3 ml per liter of water: for 10 liters take 30 ml, for 1 gallon = 12 ml
     Green leafy vegetables  Solution 1: 2.5 ml per liter of water: for 10 liters take 25 ml, for 1 gallon = 8 ml
     Solution 2: 2.5 ml per liter of water: for 10 liters take 25 ml, for 1 gallon = 8 ml
     
    When mixing the nutrients, pay attention to whether the plants show any signs of deficiency. Read more here: Signs of deficiency.
    If you have an EC or TDS meter, the concentration should be between 1.5 and 2.0 EC. Read more here: EC and pH values ​​of plants.
     
    * ) Conversion
    1 US gallon = 3.78541 liters = 231 cubic inches (inch³)
    1 liter = 0.26417 US gallons
    1 American gallon = 4 American quarts = 8 American pints = 3.785411784 liters
    Context: 
    ID: 595
     

  • Water hardness °dH

    The total hardness of the water is given in "degrees of German hardness", abbreviated to " °dH" (often also " °dGH").

    This is the equivalent concentration (molar concentration) of the alkaline earth metal ions dissolved in the water: mainly  calcium + magnesium, as well as the strontium and  barium ions , which are usually only present in trace amounts  . If a lot of calcium and magnesium ions are dissolved in the water, it is hard, otherwise it is soft.

    One °dH corresponds to 10 mg CaO (calcium oxide) per liter of water.

    Calcium carbonate consists of calcium, carbon and oxygen (CaCO 3 ).
     
    Conversion for water hardness units
      °dH°e (°Clark)°fH°rHppm (°aH)mEq/lmmol/l
    German degrees 1 °dH = 1 1,253 1.78 7,118 17.8 0.357 0.1783
    English Degrees
    (Clark Degrees)    		 1 °e = 0.798 1 1.43 5,695 14.3 0.285 0.142
    French degrees 1 °fH = 0.560 0.702 1 3,986 10 0.2 0.1
    Russian degrees 1 °rH = 0.140 0.176 0.251 1 0.146 0.050 0.025
    ppm CaCO 3
    (American degrees)    		 1 ppm = 0.056 0.07 0.1 6,834 1 0.02 0.01
    mval/l alkaline earth ions 1 mEq/l = 2.8 3.51 5.00 20,040 50 1 0.50
    mmol/l alkaline earth ions 1 mmol/l = 5.6 7.02 10.00 40,080 100.0 2.00 1

    The unit 1  ppm  is used here contrary to the actual meaning of the word in the sense of 1 mg CaCO 3  per liter of water. CaCO 3  has a molar mass of 100. This means that 1 ppm CaCO 3  = 1/100 mmol/l and is not dimensionless.

    If the values ​​for magnesium (Mg) and calcium (Ca) are known, the hardness of the water (e.g. mineral water) can be calculated as follows:

    • Hardness of water in 
    • or in 
     
     

    Hardness levels (°dH) in Germany

    Below is a list of the current hardness levels (for Germany) for your orientation:

    Hardness levelMillimoles calcium
    carbonate*    		°dH
    I = soft water < 1.5 < 8.4
    II = medium hard water
    III = hard water > 2.5 > 14

    (*Calcium carbonate per liter)

    This table contains the values ​​of the new version of the Detergents and Cleaning Products Act (WRMG) of 5 May 2007.

    To measure the total hardness, there are various reagents (drop test with color indicators) or electronic measuring devices available from specialist retailers. These tests only take the calcium + magnesium ions into account.

    Sources, among others: https://de.wikipedia.org/wiki/Wasserh%C3%A4rte

     Context: 
    ID: 596

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