Can well point water in Cape Town kill my lawn?

Discussion in 'The Lounge' started by Neville, Oct 18, 2017.

  1. Neville
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    Neville Green fingers

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    I stay in Parklands East, roughly about 5km from the nearest beach in Table View. I had a well point installed late last year but have only really started using it now on a regular basis after our dismal raining season seems to have ended.
    My lawn was coming along nicely and recovering after the dry Summer and was looking nice and green about a month ago. This mostly due to the Winter's rain, though sparse. Since then I've started using the well point water roughly about twice a week to water the lawn. Now the lawn is looking visibly "dry", just like when it was half dead in Summer due to the heat and drought.

    The well point installer did a very rudimentary test of the water by literally tasting it and confidently declared it to be salty. Being a bit more scientific in my approach, I whipped out my test kits as used on my aquariums and found the following: KH is 60 Mg/l. pH is about 5.5. Zero phosphates. Not sure what else to test?
    Besides that, the water is a very light yellow-brown and almost clear. My wife recons it smells metallic, I get rotten eggs like sulphar (is that possible?) My neighbour says it smells like dam water from a farm - I'm not sure what that means as I never grew up on a farm.

    The soil is very sandy as we are so close to the ocean and I have been using organic manure and other organic fertilisers as supplied by regular local nursary. Also been dosing a product called Gold Dust which I believe is calcium based and is alleged to increase the sandy soil's water retention and sold by all the nurseries in the Table View area. Recently got told by a seemingly knowledgeable nursery staff member that the calcium in the Gold Dust also helps to separate the salt from the soil, if indeed my well point water is saline.

    Am I close enough to the ocean to still have salt water entering the underground water? My wife says they had a well point at her parents house half as close to the ocean and had no trouble with salt water.
    Where can I get it tested more scientifically and what should I test for?
    If need be, is desalination practical for home garden use? I know the yachts have such systems installed that produce drinking water although my budget is not quite in the yacht owners' bracket.

    Or is it the soil that I need to test?

    Any advice much appreciated.
     
  2. Trev Pleco
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    Trev Pleco Algae destroyer

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    here is the test I had done, you could try them..

    WT005053.jpg
     
  3. Olivier
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    Olivier Green fingers

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    If you suspect salt in your water you can first check the specific gravity.
    I can do that for you if you want, I stay 5 minutes away from you.
     
  4. Neville
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    Neville Green fingers

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    Trev, can you explain some of your results please? E.g. what are the good and bad "ingredients" (for lack of a better term) of your water for the purpose you intend using it?
     
  5. Neville
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    Neville Green fingers

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    That will be awesome. Will PM you to arrange.
     
  6. Hendre
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    Hendre Plant menace

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    Did the lawn go brown? If so then it's iron, very common in groundwater around here.
     
  7. Neville
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    Neville Green fingers

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    Yes, like light brown yellowish ... just like dry grass in Summer
     
  8. Joshua Tree
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    Joshua Tree Valued Contributor

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    Firstly, do you have a wellpoint or a borehole? If it's a wellpoint your pump is on the surface and is usually 0.75kw. These pumps will only draw approximately 6m below surface. What is your elevation above sea level?

    What type of grass are you growing?

    If it smells like eggs it usually means you are drawing water through peat (decomposed vegetable/plant matter) which is generally good for your garden.

    Silly question but have you tasted your water? Does it taste salty?

    As Trevor showed you a lab will give you a full analysis of your water then look at the very high and low components to see what effects these might have on your grass type.
     
  9. Neville
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    Neville Green fingers

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    As in my original post, it is a well point. It extracts from about 8m as that is how the installer set it up. When he drilled he actually found water from 5m but went a bit deeper ti cater fir the water table dropping during summer.
    It is new development about a year old where the developer put down mixed sods. So there is kukuyu, cynodon and bits of a third, very fine leafed grass I can not id. I can post pics if you can id it.
    Yes, I did taste it and l think it dies taste slightly salty. We are also quite close to the Rietvlei spruit in the Table view nature resort.
    We should be pretty close to see level as it is a flat, 5km drive to the beach.
     
  10. Neville
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    Neville Green fingers

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    [​IMG]

    Sent from mTalk
     
  11. Hendre
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    Hendre Plant menace

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    There we go... Many people use iron filtration with their WellPoint systems
     
  12. Neville
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    Neville Green fingers

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    Yeah, I'll look into the iron filtration, thanks.

    Next question: how much iron is too much for the garden?
    I see other gardens in the area with well-points and the walls and curbstones are red-brown from the iron. Their grass is green and healthy though. I suspect I've been under-watering as my lawn gets dried out by the wind despite it not being hot at the moment.

    FWIW, Olivier did the salt test for me and suggests that is not my problem. His results: Specific gravity = 1.003 and TDS = 84 ppm.
     
  13. Olivier
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    Olivier Green fingers

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    D
    Does the color match the 1mg/l? Hard to see on the photo but it looks like it's darker meaning above that level.
    Iron is beneficial to plants but an overdose can occur.
    I doubt you have too much iron due the TDS reading.
    As discussed try to water more often and maybe get a lab to test you water.
    Due the bad smell I suspect sulfurs.
     
  14. Neville
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    Neville Green fingers

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    Sorry for delayed response...

    Yes, it is definitely darker so above 1mg/l. I am worried about overdose...
    As suggested here I started watering more often and this did seem to help for a while. There was definitely some new growth in the dryer parts of the lawn and it was looking to be recovering. Now, it is the opposite again. I water daily and always check the soil before I do so. On cooler days when the soil does not dry out completely from the previous watering, I do not water as I'm trying to be a responsible water user.
    However, now I'm seeing dry, dying patches again like when I wasn't watering enough. Now that I'm watering more often, can I have reached the limit where the iron is now overdosed and killing the grass?
    No, I haven't done a full lab test of the water yet, just above home tests.

    BTW, anyone know of any active gardening forums based in SA? I searched a bit and found only one that does not seem very active at all. I though South Africans like their gardens...? Or perhaps the typical gardener is not a typical internet user...
     
  15. Trev Pleco
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    Trev Pleco Algae destroyer

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    Sorry @ Neville, just saw this query now.

    Wish I could fully explain it, I was hoping one of the water chemistry wise folk could..?

    As advised by Dirk, I have in the passed mixed the well point 50/50 with municipal supply and the results were fine. I have not done so with shrimp given the high TDS although it seems fine for neos. Given we can no longer use municipal water in the Cape, I now buy RO water for the caridina and also mix this 50/50 with the well point for neos. I have always used the above water for a large koi pond and no issues.

    I'm currently converting the well point for domestic supply and have been advised by a water engineer that all I need to do is raise the pH for my piping which is pretty standard and then precautionary UV treat for any potential nasties that might get into the supply. I'm just working out how I need to put this all together as have purchased a 2500lt tank for domestic which will feed from the x2 10k irrigation tanks..
     
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