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making a 4dKH solution using a teaspoon?

J

jarthel

Member
Joined
12 Nov 2009
Messages
212
All I have is a weighing scale (use for measuring a person's weight) so I decided to check out what tutorial is available out there using a teaspoon/tablespoon.

I found this site.

It says:
•Dissolve 1 teaspoon (6 grams) of sodium bi-carb into 1 litre of distilled water.
•Take 10mL of this solution and dissolve it further into 490mL of distilled water.

Any thoughts on this guide?

thank you very much :)
 
aaronnorth said:
Accuracy is the key to making this solution, and teaspoons just aren't accurate enough.
You can get 0.1g scales for about £6 on ebay
Click to expand...

yup. I already watching a .01 scale in ebay. just wondering if I should buy it :)

-----------

thanks everyone :)
 
In something of a similar situation to what Jarthel was.

No supplier of a 4dkh here in Australia( that I can find ), so wondering whether it is recommended to make your own, or is there too many factors that could result in things going dire.

would appreciate some help on this,
cheers thanks
tel
 
Hi all,
You can make your own from "baking powder" (Sodium bicarbonate - NaHCO3), you can also get around the problem of needing accurate scales if you use fairly large weights and lots of dilutions (plastic measuring spoons or kitchen scales should be fine). You don't need to be able to measure volumes all that accurately either, as 1000ml (1 litre) of water (or dilute solution) weighs 1000g (1kg).

I've lifted this straight from Wikipedia, but it is correct.

"An aqueous solution containing 120 mg NaHCO3 (baking soda) per litre (1000ml) of water will contain 1.4285 mmol/L of bicarbonate, since the molar mass of baking soda is 84.007 g/mol. This is equivalent in carbonate hardness to a solution containing 0.71423 mmol/L of carbonate, or 71.485 mg/L of calcium carbonate (molar mass 100.09 g/mol). Since one degree KH = 17.848 mg/L CaCO3, this solution has a KH of 4.0052 degrees."

120mg = 0.12g but we could make the initial solution a lot more concentrated, 1.2g = 40KH and 12g = 400KH.
(This is where we get the initial "6g in 500ml" from, 6g in 500ml = 12g in 1000ml.)

So 12g in 1000ml = 400KH I'll all this "solution 1", and 100ml of solution 1 in 1000ml = 40KH "solution 2", and then 100ml of solution 2 in 1000ml = 4KH "solution 3" and solution 3 is the one you want.

So you can make a litre of 4dKH solution for the cost of 12g of Baking Soda.

cheers Darrel
 
Thanks Darrel :thumbup: ,
I have looked at a few DIY threads floating around the various forums, as always though, some conflict as to which method is best.
cheers and thanks
tel
 
dw1305 said:
Hi all,
You can make your own from "baking powder" (Sodium bicarbonate - NaHCO3), you can also get around the problem of needing accurate scales if you use fairly large weights and lots of dilutions (plastic measuring spoons or kitchen scales should be fine). You don't need to be able to measure volumes all that accurately either, as 1000ml (1 litre) of water (or dilute solution) weighs 1000g (1kg).

I've lifted this straight from Wikipedia, but it is correct.

"An aqueous solution containing 120 mg NaHCO3 (baking soda) per litre (1000ml) of water will contain 1.4285 mmol/L of bicarbonate, since the molar mass of baking soda is 84.007 g/mol. This is equivalent in carbonate hardness to a solution containing 0.71423 mmol/L of carbonate, or 71.485 mg/L of calcium carbonate (molar mass 100.09 g/mol). Since one degree KH = 17.848 mg/L CaCO3, this solution has a KH of 4.0052 degrees."

120mg = 0.12g but we could make the initial solution a lot more concentrated, 1.2g = 40KH and 12g = 400KH.
(This is where we get the initial "6g in 500ml" from, 6g in 500ml = 12g in 1000ml.)

So 12g in 1000ml = 400KH I'll all this "solution 1", and 100ml of solution 1 in 1000ml = 40KH "solution 2", and then 100ml of solution 2 in 1000ml = 4KH "solution 3" and solution 3 is the one you want.

So you can make a litre of 4dKH solution for the cost of 12g of Baking Soda.

cheers Darrel
Click to expand...


Hi Darrel,

Thanks for the info but at the risk of seeming pedantic you must first start with pure H2O for the above to work. i.e. Distilled or RO water. I know its just an oversight on your part mate but just to save someone somewhere some confusion further down the line I felt it needed pointing out.

Regards, Chris.
 
Hi all,
Yes you would need to start with de-ionised water, I must admit it didn't occur to me that any-one would do anything else, which I suppose is a bit of an oversight on my part. Having said that because you are using relatively small amounts it would be economic to buy it.
cheers Darrel
 
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