Kh Test Kit- How To Use? Question

  1. Gersh Member Member


    I got this KH test kit from my LFS, but it didn't have any instructions on how to use it. Anyone used this one or know how to use it?
  2. AllieSten Fishlore VIP Member

    Yep. I have.

    So what you will do is get 5ml of tank water in your vial. Now take the kH drops and add one drop, put lid on vial, turn vial up and down a couple times. This will count as 1 drop. The water should have turned a very very light blue color. You may need a white paper to hold up next to it to see the color difference.

    Then you will count drops. So add a drop, put lid on, invert test tube. Add drop, put lid on, invert test tube.

    You will add each drop individually. However many drops it takes to turn the water from Blue to bright yellow is your kH value.

    Here is the instructions online and the actual chart for numeric value versus drops.

  3. Gersh Member Member

    Ok. SHould the solution in the bottle be orange? I tried this and my water seemed yellow after a single drop.
  4. AllieSten Fishlore VIP Member

    Ohh well after 1 drop then your kH is 0. As low as it can get.

    Be sure you are testing your tap water and your tank water both. So you can see where the problem is.

  5. Gersh Member Member

    I tested both and both were yellow almost immediately. Should the solution be orange in the dropper?
  6. -Mak- Well Known Member Member

    The color in the bottle is the color the liquid should turn to after the test is complete. Orange sounds about right. 0 kh will make your water prone to drops in ph, it's a good idea to add some crushed coral or other calcium carbonate sources to your filter to boost the kh a bit.
  7. Gersh Member Member

    Alright! I'll have to do that then. And it explains why my pH has gone from 7.8 to 6 overnight

  8. AllieSten Fishlore VIP Member

    Yep. That would do it. You need to add some calcium carbonate to your tank, to buffer the water. It will raise your kH and then raise your pH.
  9. Gersh Member Member

    And the best way to do that is crushed coral?
  10. jdhef Moderator Moderator Member

    Using crushed coral is a good way to raise your KH (it's the method I use), but you could also use a cuttle bone (those things you find in the bird department at the Pet Store).

  11. Gersh Member Member

    I'll probably do that so I can put it in the filter and keep it out of site. Do you ever have to replace it?
  12. jdhef Moderator Moderator Member

    The crushed coral dissolves slowly over time, so eventually you will need to replenish it.
  13. Raimy101 Initiate Member

    Some would say yes you should replace. I left a small piece of cuttle bone in my tank and it i has slowly disolved to half its original size.
    I think as long as it doesn't show any type of growth to indicate it being rotten it is fine to leave long term.
  14. Gersh Member Member

    Alright. How do you figure out how much you need? I have a 55g but don't know how much coral I should get.

    I found a couple places where people used backing soda to raise their KH. They're saying it's more precise and measurable compared to the crushed coral. Is it possible to do?
  15. Raimy101 Initiate Member

    I would personally stay away from baking soda. For crushed coral several chunks will work or about a third of a cuttle bone will do. The cuttle bone will float at first until it becomes water logged.
  16. jdhef Moderator Moderator Member

    The crushed coral method is pretty much set it and forget it. With baking soda, you need to threat the water with every water change and also need to be careful not to change the hardness too quickly by either using too much or not enough.

    When using crushed coral, it is a trial and error process to see how much you will need. You add some, wait a few days, test pH add more if required, wait a few days, test etc. But for a 55g tank, I would start with somewhere between 1/3 and 1/2 cup.
  17. -Mak- Well Known Member Member

    Also, baking soda is not calcium carbonate, it is sodium bicarbonate. While I'm not sure of the effects of it vs calcium carbonate, or if the sodium is an issue, just note it could be slightly different because it is not the same stuff that crushed coral or animal carbonate products are.
  18. AllieSten Fishlore VIP Member

    The “dose” for the crushed coral is 1 cup for 40 gallons of water. So adjust accordingly. If after 36 hours your pH hasn’t stabilized above 7.0 then add 1/4 cup per 40gallons every 12 hours. Usually you will stabilize somewhere between 7.4-8.4.