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  1. #1

    How to test for KH.

    Hi Everyone/ Hope everyone is well. I've been checking my KH with a API test kit. And it states on the instructions that you should add drops until it start turning bright yellow. But I've seen a lot of videos showing them taking the reading from the point it turned yellow. Can anyone please shed any light on this? Thank you



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  3. #2
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    My tap is pretty much 0 so have to dose with bicarb

    I add drops till it turns blue . Normally 3,4 as that's what I like to keep mine at

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  5. #3
    There is often confusion regarding how to do KH and GH tests and especially how to interpret the results. Apart from using different reagents the method is the same for either the KH or the GH test and is simple if you follow these five steps:

    1. Take the sample and, if the kit manufacturer states that an initial reagent is required then add it, if not proceed to step 2 to determine the value of KH or GH.
    2. Add one drop of the test reagent at a time. Don’t shake vigorously to mix, simply swirl or use a plastic stirrer.
    3. Note the initial colour after the first drop and continue adding drops until the initial colour JUST BEGINS to change. (This is called the end point).
    4. Count all drops added in steps 2 & 3, including the first one. It is sometimes incorrectly stated on forums that the first drop should not be counted.
    5. The value of °KH or °GH is given by the number of drops used. (Multiply by 17.8 to convert to mg/L / ppm or see the table).

    The change is normally very abrupt but, in rare cases, if it is just on the edge of the transition from the initial colour to the final colour, it will be half way between the two and this can be confusing (see the end point diagram). If you aren’t sure if you have reached the transition, you can add an extra drop to make certain. This will complete the colour change and confirm that the previous drop had already reached the end point but don't count this extra drop.

    Interpreting the results in degrees (KH or GH):

    Colour change happens after:
    1st drop the value is between 0 and 1.0 degrees (°KH or °GH)
    2nd drop the value is between 1.0 and 2.0 degrees (°KH or °GH)
    3rd drop the value is between 2.0 and 3.0 degrees (°KH or °GH)
    And so on.

    A more precise way to measure the value, especially when the KH or GH is low is to use twice the recommended sample size then each drop counts as 0.5 degrees e.g.
    1st drop indicates 0 to 0.5 degrees (°KH or °GH)
    2nd drop indicates 0.5 to 1.0 degrees (°KH or °GH)
    3rd drop indicates 1.0 to 1.5 degrees (°KH or °GH)
    And so on.

    For very low values, an even more precise way, is to use four times the recommended sample size, then each drop counts as 0.25 degrees. This is very accurate but uses a lot of reagent so is only suitable for low values. Using the usual recommended sample size so that one drop of reagent = 1 degree is sufficiently accurate for normal values of KH or GH.



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  7. #4
    Thank you Johnathan.

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  9. #5
    Senior Member Rank = Supreme Champion davethefish1's Avatar
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    Syd's explaination was far better than the one i was writing
    Last edited by davethefish1; 20-05-2022 at 01:33 PM.

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  11. #6
    Quote Originally Posted by Manky Sanke View Post
    There is often confusion regarding how to do KH and GH tests and especially how to interpret the results. Apart from using different reagents the method is the same for either the KH or the GH test and is simple if you follow these five steps:

    1. Take the sample and, if the kit manufacturer states that an initial reagent is required then add it, if not proceed to step 2 to determine the value of KH or GH.
    2. Add one drop of the test reagent at a time. Don’t shake vigorously to mix, simply swirl or use a plastic stirrer.
    3. Note the initial colour after the first drop and continue adding drops until the initial colour JUST BEGINS to change. (This is called the end point).
    4. Count all drops added in steps 2 & 3, including the first one. It is sometimes incorrectly stated on forums that the first drop should not be counted.
    5. The value of °KH or °GH is given by the number of drops used. (Multiply by 17.8 to convert to mg/L / ppm or see the table).

    The change is normally very abrupt but, in rare cases, if it is just on the edge of the transition from the initial colour to the final colour, it will be half way between the two and this can be confusing (see the end point diagram). If you aren’t sure if you have reached the transition, you can add an extra drop to make certain. This will complete the colour change and confirm that the previous drop had already reached the end point but don't count this extra drop.

    Interpreting the results in degrees (KH or GH):

    Colour change happens after:
    1st drop the value is between 0 and 1.0 degrees (°KH or °GH)
    2nd drop the value is between 1.0 and 2.0 degrees (°KH or °GH)
    3rd drop the value is between 2.0 and 3.0 degrees (°KH or °GH)
    And so on.

    A more precise way to measure the value, especially when the KH or GH is low is to use twice the recommended sample size then each drop counts as 0.5 degrees e.g.
    1st drop indicates 0 to 0.5 degrees (°KH or °GH)
    2nd drop indicates 0.5 to 1.0 degrees (°KH or °GH)
    3rd drop indicates 1.0 to 1.5 degrees (°KH or °GH)
    And so on.

    For very low values, an even more precise way, is to use four times the recommended sample size, then each drop counts as 0.25 degrees. This is very accurate but uses a lot of reagent so is only suitable for low values. Using the usual recommended sample size so that one drop of reagent = 1 degree is sufficiently accurate for normal values of KH or GH.


    Hi Manky. Thank you for the reply something to sink my teeth into, love the in depth details. I will get out there now and do the retest. Because the leaflet states bright yellow, I may have added an extra 4,5 drops from first turning faint yellow to bright yellow. Thank you

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  13. #7
    Quote Originally Posted by davethefish1 View Post
    Syd's explaination was far better than the one i was writing
    Thank you Dave.

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  15. #8
    Hi/ Tested the water KH=2degrees. GH=9 degrees.

  16. #9
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    Definitely boost with bi carb mate

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    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  17. #10
    Quote Originally Posted by Ajm View Post
    Definitely boost with bi carb mate

    Sent from my SM-G973F using Tapatalk
    Thank you Johnathan

  18. #11
    You can ignore GH, it has no effect on koi health but a low GH will allow fish with predominant beni (red) colouration such as kohaku to develop to the full extent that their genetics will allow. A high GH is better for sumi (black) development. See this article on my website for a full explanation of the effects of hard or soft water on koi colour development:
    Chromatophores

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  20. #12
    Quote Originally Posted by Manky Sanke View Post
    You can ignore GH, it has no effect on koi health but a low GH will allow fish with predominant beni (red) colouration such as kohaku to develop to the full extent that their genetics will allow. A high GH is better for sumi (black) development. See this article on my website for a full explanation of the effects of hard or soft water on koi colour development:
    Chromatophores
    Thank you for your reply Manky. So as long as the KH at 2 is stable, would it be ok? I will check my tap water. I monitor my water now every two days. And I have cut my food down 20gms, water temp is about 16c. Thank you again.

  21. #13
    If you run a KH as low as that, you would be taking on the commitment to make sure that it doesn't fall any lower and put your pond at risk of a pH crash.

    However, if you're happy to do that and there are back up arrangements for someone else to monitor it if you go on holiday or become ill and confined to bed then, as long as the pH is stable at that level, you would be OK.

  22. #14
    Quote Originally Posted by Manky Sanke View Post
    If you run a KH as low as that, you would be taking on the commitment to make sure that it doesn't fall any lower and put your pond at risk of a pH crash.

    However, if you're happy to do that and there are back up arrangements for someone else to monitor it if you go on holiday or become ill and confined to bed then, as long as the pH is stable at that level, you would be OK.
    Thank you Manky. I've checked the tap water and that is also 2dkh. So I haven't got a deal of head room. And when I up my food,when it get's warmer I could soon come unstuck. And I'm going to be adding a diy trickle filter. So that would hammer the KH too! At the moment their only in a 700gallon swimming pool, why I build the pond. So I going to try adding 10grams of bicarbonate of soda a day until I can get it around 5dkh. Good call Jonathan. And thank you again Manky.

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  24. #15
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    Has any one heard from john1 lately he would have been all over this as he is in same boat as me with 0kh at source . Just realised ain't seen him post for a little while

    Scratch that his profile says he's been on today

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  25. #16
    Senior Member Rank = Supreme Champion davethefish1's Avatar
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    Quote Originally Posted by Maddog1 View Post
    Thank you Manky. I've checked the tap water and that is also 2dkh. So I haven't got a deal of head room. And when I up my food,when it get's warmer I could soon come unstuck. And I'm going to be adding a diy trickle filter. So that would hammer the KH too! At the moment their only in a 700gallon swimming pool, why I build the pond. So I going to try adding 10grams of bicarbonate of soda a day until I can get it around 5dkh. Good call Jonathan. And thank you again Manky.
    sodium bicarbonate is one of those things that everyone should have on hand,
    especially if your tap water is low in Kh.

    like ST, it's cheap as chips...
    £12 for 5KG in a bucket, or £26 for 25kgs in a sack....
    and if kept dry doesn't really have a shelf life....

    the pityful amounts you can buy in a supermarket if you need it in a hurry,
    compared to ordering 5 - 25kgs online and waiting a day or so...
    Last edited by davethefish1; 20-05-2022 at 10:13 PM.

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  27. #17
    Quote Originally Posted by davethefish1 View Post
    sodium bicarbonate is one of those things that everyone should have on hand,
    especially if your tap water is low in Kh.

    like ST, it's cheap as chips...
    £12 for 5KG in a bucket, or £26 for 25kgs in a sack....
    and if kept dry doesn't really have a shelf life....

    the pityful amounts you can buy in a supermarket if you need it in a hurry,
    compared to ordering 5 - 25kgs online and waititng a day or so...
    Thank you Dave. I did wonder about that, went to morrisons and bought 180g for £1.25.

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  29. #18
    Yeah, just seen on amazon £26 for a 25kg, works out at £1.08 a Kilo

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  31. #19
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    https://www.ebay.co.uk/itm/125132991...mis&media=COPY

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    Freddyboy the legend

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    Johnathan

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  33. #20
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    23.99 for 25kg

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    Freddyboy the legend

    "we are water keepers first"

    Johnathan

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