hard water and nutrient uptake

Discussion in 'Plant Help' started by samc, 21 Dec 2009.

  1. samc

    samc Member

    28 Oct 2008
    i have just read an article by amano which suggests that hard water prevents a plants uptaking max nutrients. seeing as i have the hardest water area in the uk (very hard) this may be affecting my plant growth. i have never been able to grow stems to look 'lush' they allways look as if they are missing something, even when double dosing EI. and seeing as stems are fast growers this may be the cause. i was thinking with all the snow about it may be a good idea to stock up on soft clean water

    do you guys have any views on this?
  2. aaronnorth

    aaronnorth Member

    19 Feb 2008
    worksop, nottinghamshire
    where do you live? Have you tested/ can you get a water report online?
    The water in my area is pretty hard,
    KH 8
  3. chump54

    chump54 Member

    28 May 2008
    Thorington, suffolk
    Sam... how hard is your water? i'm in suffolk and feels like we have the hardest water in the country :lol:

    my water is 28.7 german hardnesses (from local water authority info)

    anyway I have been using a mix of RO and tap in my 125l tank because I was concerned about how hard my water is. but in my nano I went for straight tap to test it out. It seems to be fine, no probs other than water marks :crazy: the growth is a lot slower but I'm only using easy carbo in the nano so it's not a straight forward comparison. I have switched to 100% tap on the 125l (2 weeks ago) everything is still growing as it was but it's still very early days.

    I'll be interested in other peoples ideas on this too.

  4. samc

    samc Member

    28 Oct 2008
    thanks for the replies. i thought knowone would have any ideas on this one.

    just looked on the online water report and its 16 deg. but then a mile up the road its 21 deg :lol: anyway its pretty high so i am going to try mainly soft water and see if it has any inpact.

    other views would be interesting
  5. samc

    samc Member

    28 Oct 2008
    just as a reference, this is a average amano tank with 'hard' water
    TH ----------------------------50mg/l--------112.8mg/l :wideyed:
    NH4 (amonnium)------------0mg/l----------0.5mg/l <---i have ammonia before i start :lol:
    NO3---------------------------0.0mg/l-------50mg/l :wideyed:

    sorry about the dashes. it automatically takes spaces out :lol:
  6. dw1305

    dw1305 Expert

    7 Apr 2008
    nr Bath
    Hi all,
    Sam your water is horrible, 50mg/l is the maximum legal limit for nitrate in drinking water in the UK.
    Your water will definitely limit the availability of P, Mg & Fe to a lot of plants, due to the formation of insoluble compounds (P & Fe), and the unfavourable Mg:Ca ratio. If you want lush plants probably your best bet is to find plants that naturally grow in hard water, as they tend to have adaptations to gather the problematic nutrients in hard water.
    cheers Darrel
  7. samc

    samc Member

    28 Oct 2008
    hi darrel :wave: thanks for the reply

    i have allways had a slight FE deffiency with my stems so that may well be the cause :thumbup:

    i do have an ro unit. but i am on a meter so my uncle uses it for his reef tank and runs me off about 30l when needed so i might get him to do that every couple of weeks and that should help
  8. plantbrain

    plantbrain Expert

    2 Aug 2007
    I do not think the ratio of Mg:Ca has beans to do with plant growth other than above an absolute value for each as limiting nutrient, => Liebig's law. Least that is what all the mineral nutrition experts here say (Dr Bloom, he's down the hall from me at UCD, see Epstein and Bloom for a text on mineral nutrition in higher plants) and practical experience dosing and using hard water. Ratios can build up much higher on soil particles in terrestrial systems as evaporation occurs, this is not an issue in aquatic systems.

    I think Amano was referencing specifically to Alkalinity, not pH/GH.
    GH has no effect and Ca/Mg are both plant nutrients and even at GH of 25 in Santa Barbara, and a KH or 11, I had little issue growing most species when using CO2.

    Here's some tanks I had:




    Here's L cuba growing just fien outside in the nasty tap of Davis CA, GH is 14, Mg is 50+ ppm alone...........KH is 18........


    I agree the water listed is foul, I would not drink it.
    I'd use an RO unit and use that.

    And in general, if you can reduce the Kh to 5 or less, the easier it is for most plants to grow well.
    For most aquatic weeds, hardwater(GH and KH) means more weeds, not less.

    for us, it's nicer to have soft water, if we want hard water, we can simply add baking soda or GH booster.
    Low KH, moderate to high GH is ideal for all species.

    I cut the Davis tap with 60% RO to get this tank full of wimpy softwater species:


    So it's still fairly hard.........for both KH and GH.

    Results speak more than theory, but I agree in general, lower KH is better, I disagree about GH.
    I think it's much more about the KH causing issues, likely with CO2 and carbon allocation in aquatic plants than uptake of specific nutrients being "blocked". Some simple test can show that they are not being blocked.

    Advice: get an RO unit, drink that RO water, not the tap.

    Tom Barr
  9. freewolny

    freewolny Member

    31 Oct 2019
    And this is lethal advice. Don't do that to yourself and don't do that to your kids - drinking a RO water especially in long terms leads to serious health problems, including death from cardiovascular disease.
    Last edited: 10 Nov 2019
  10. Aqua sobriquet

    Aqua sobriquet Member

    17 Mar 2012
    I live in a fairly hard water area but thanks to Darrel‘s suggestion I’ve been using rainwater in my two Nano’s. Plants seem to be growing well and no nasty white sediment on the glass and equipment.

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