General Hardness question.

Discussion in 'Aquarium Water' started by flyin-lowe, Apr 1, 2010.

  1. flyin-loweWell Known MemberMember

    Today I picked up a Sera brand GH test kit. The directions say to add the reagent until the water goes from red to brown to green counting each drop. Number of drops equals hardness. I first tested my tank water (well water/water softener.) I put in the first drop and the water had a slight green tint. Each drop it got more green, never red or brown, so I am assuming my GH is between 0-2. To make sure the test works I went out to my hose and tested the water and it tested about 19. I then tested the water straight out of the faucet (again well/softener) and it tested the same as the tank water 0-2.
    Is the results from the water softener a true representation of the water hardness my fish experience or does the softener alter the test results.
    The reason I ask is I am going to stock my tank with cardinal tetras and angel fish. I have been told and read that they prefer softer water (which my test indicates I have). I also noticed in the profile it recommend a hardness of 5-10dH. What exactly is dH and is it different the GH. Do I need to get a more specific test kit or is my GH kit ok.
    My pH was sky high and I removed a few rocks that I think were causing the problem. I then did about a 25% water change and the pH was 8.2 (still high). I'm hoping it comes down a little more as my well water test 7.4-7.6 depending on which solution I use. What correlation if any is there between hardness and pH.
  2. mathasWell Known MemberMember

    • GH: "General hardness", this is a measure of mineral content, often calcium and/or magnesium.
    • dH: German "degree hardness", this is a measure of GH. One German degree hardness (dH) is 10 mg of calcium oxide (CaO) per liter. In the U.S., hardness is usually measured in PPM of CaCO3. A German dH is 17.8 ppm CaCO3.
    • KH: "Carbonate hardness" or "alkalinity", this is a measure of bicarbonate (HCO3-) and carbonate (CO3--) ions in the water. This is the water's buffering capacity against pH swings.
    For more detailed information, try the following links:

  3. flyin-loweWell Known MemberMember

    So is it safe to assume that since my GH is close to 0 then my KH is ok??
  4. mathasWell Known MemberMember

    What do you mean by "ok"? Low GH often (though not always) means low KH, which in turn means your tank is more susceptible to pH swings.

    As one of the links above says:
  5. flyin-loweWell Known MemberMember

    I am just curious, I have never had an RO unit so I don't know a lot about them. Is there a way to plumb one in so I could hook my Python up to it or do you have to put the water into holding tank and then transport it. I would consider buying one but with a 120g tank I hate the thought of having to haul water across the house. Plus I hate the thought of spending the bucks on a Python and not being able to use it.

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