Given the wide ranges of
KH related issues and suspiciously high
CO2 ppm readings in some folk's tap water/tank water, this
KH reference method is a very useful thing.
The hardest thing is getting folks to actually make one and calibrate things.
So I did some digging and have a couple of useful links that make it clear.
Here is a good
KH Calculator using baking soda to make your
KH reference sample.
http://www.cnykoi.com/calculators/calckh.asp
Note: make larger volumes(5 liters) and high concentrations, and then dilute.
This reduces errors(less is better).
So adding 5l of
DI H2O (1.321 gallons) and 4.992 grams of baking soda = 40KH.
Play around with the calculator, try 50 liters and 4
KH, the higher volumes and higher the concentration, the less error you have, well up to a point[:p]
50 liters of
DI water and 40
KH will give you 49.923 grams.
Now you have pretty high accuracy but you have a lot of
KH solution!!
5 liters is not bad and you can toss the rest down the drain or trade to friends etc in the hobby.
Then you may take a 10ml sample of the 40KH reference and add it to a 90mls of
DI water.
This will give you a reference of 4
KH to within a very close tolernace depending on how careful you are weighing the baking soda, measuring the water volume and cooking the baking soda for 30-45 min at 400F before weighing to remove water and
CO2 in the baking soda.
For diutions:
http://www.wellesley.edu/Biology/Con...etovolume.html
This should help you get going on making the
KH reference solutions and putting them to good use.
You may use the drop checker method, it's slow, cheap, simple, or you can DIY a DO membrane on the tip of a pH probe, and put the
KH ref solution inside instead of the dissolved
O2 KCL solution.
This is extremely accurate.
DO membrane material is fairly cheap per unit.
Regards,
Tom Barr
Linear Mode
