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Another DIY 4*dkh Solution

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Ok, so I decided to see if I could come up with another simple and somewhat accurate method to make 4* dkh for my co2 drop checker. This is what I came up with, I verified my results by duplicating the test 3 times and ending up at the same result each time.

Couple primers to start:
- I use my own RO/DI 0 tds water for the solution
- I use a calibrated HM Digital TDS meter
- I use API's Kh test kit
- I have used both Seachems Alkaline Buffer and Baking Soda and both test out the same
- I used everyday CLEAN containers and measuring cups/spoons that are used only for my tanks use and cleaned/rinsed with RO/DI water
- I do have lab testing background and have made very accurate 4* solutions but wanted to come up with another A.S. version for the casual hobbyist.
- No it will not be "laboratory" grade/accuracy but in my experience it is close enough for the casual hobbyist.
- I have been in the hobby for over 20 years but new to the forum

1. Start with 6 cups of 0 TDS water in a clean measuring container
2. Add 1/8 tspn Sodium Bicarbonate to the 6 cups of water and mix
3. Pour out 3 cups of this mix and discard
4. Add back 3 cups of 0 TDS water and mix
5. Pour out 3 cups of this mix and discard
6. Add back 3 cups of 0 TDS water and mix
7. Pour out 1 cup of this mix and discard
8. Add back 1 cup of 0 TDS water and mix
7. Water comes out to +/- 70 ppm TDS and will test @ 4* DKh solution

Any questions or comments welcomed. And if someone has the same basic matierals, I would like to hear if you were able to duplicate my results :)


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233 Posts
Discussion Starter · #7 ·
Go right ahead Hoppy

And yes, quite a bit of waste water and overall solution when completed. But to err on the more accurate side is why I went with the amounts I did. One could half all these measurements and end up with less waste/product, but as mentioned I prefer to work in larger quantities.

233 Posts
Discussion Starter · #14 ·
Glad to hear you will give it a shot!

But mind that unless you are able to verify that you are starting at 0 tds or damn close, results cannot be guaranteed. I found that if tds rose to around 74-76, it threw of the dkh slightly.

When I was working in a lake biology lab, seemed they would get lazy on the ro filter maintanance. Wonder if that's what issues your lab had also, Lol.
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