Pond Water Hardness

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I was delighted to get an email from Brenda B. who is a subscriber of ours and had been battling pond algae in her small pond. She was dedicated to working with bacteria to clean things up but wasn’t getting the results she had hoped for.

Through her own research she discovered that the municipal water supply she used in her pond was very deficient of minerals and what one might consider soft water. As she pointed out, and rightly so, this isn’t the best type of water for a pond because many natural pond treatments require some minerals in the water to work well. And once she was able to address these deficiencies (by adding crushed coral to add calcium carbonate) the pond cleared up quite nicely.

This is a good example of why testing for water hardness is a good idea. Many combination test strips (like our 5 in1) will test for this and it’s quite easy to adjust the mineral content of the water if you find something lacking.

In the video below I cover water hardness readings and what might be considered adequate and offer a few basic tips to improve the mineral content of pond water.

[youtube width=”425″ height=”355″]http://www.youtube.com/watch?v=q0CyVs8xqwc&feature=youtube_gdata[/youtube]

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7 thoughts on “Pond Water Hardness”

  1. Hello Mark,
    I did not get a response to my comment after the ph video so i’m posting again…it is still appropriate.
    I enjoy and look forward to your videos…you do a great job with topics and getting to the point. My issue is with balancing ph and kh. inorder to keep the kh above 125 the ph will be between 8.5 and 9. source water is about 7.8 but very low kh. I have a somewhat typical 6000 gal. pond with skimmer and bead filter. I am also running a homemade counter current foam fractionater along with a homemade device as a fluidized bed with crushed oyster shell i’ve used buffering products but i dont think the fish like them… baking soda seems to work best added at filter cleaning ( water changes)…in my situtation is there a way to keep kh at around 150+ and ph close to 8.0 Thanks, Jack

  2. Mark: The water hardness is extremely high in my pond. The Ph is somewhat elevated also. How do I reduce the hardness. The municipal water supply here in Las Vegas is very hard.

  3. Hi Jack,
    Based on my experience at least you’re doing what I would already suggest. Calcium carbonate (coral) and baking soda can often help with kH but not always dramatically affect pH. When I get a breather I may do a bit more research on this and try to update you. In the meantime if you do come across something else (in addition or otherwise) that may help, please do let me know and I’ll archive it in my mental vault:)

  4. Hi Franny,
    I think this is a question that will come up a fair amount so thanks for asking.

    In areas of the country with hard water there are a couple of options. If it’s a municipal supply some folks run their pond source water (garden hose) from the home and have a water softener to help with this.

    If this isn’t practical to do, peat moss can help soften the water by binding to calcium and magnesium in the water and it releases some light acids into the water.

    Place this in a bag in the skimmer, biofilter basin or someplace where there’s some water flow.

    It does release some tannins in the water which can turn it yellowish so it’s not a bad thing to add in some activated carbon to the pond as well.

    And of course as you go through this you’ll wan to keep testing the water to see how things are changing.

  5. Mark,
    Based on this video about water hardness I did some research and discovered that my municipal water supply is 130mg Calcium carbonate/liter. Another site suggested 210-320 calcium carbonate/liter is needed for trapdoor snails, which I have. Also in my search I discovered that egg shells are Calcium Carbonate. So I added egg shells to my water fall and low and behold the water is noticeably clearer.

    Thanks for the video I never would have headed down this path without it.


  6. Thanks for all the helpful tips. Your responses in the comments are also very helpful! I appreciate the responses and input! I will have to come back with any pond questions.

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