Detlef

If you used say: 1000mls instead of 100 and 6.0 grams instead of 0.6grams you'll get two more significant figures. Cook the baking soda prior, make the solution and it should be a good deal more accurate.

Highly accurate KH ref solution will provide highly accurate readings.
We can do this with KNO3 to less than 1ppm.
Same deal here.

But.......as you suggested, make a concentrated version, then do the dilutions, this is a much more accurate method for rather obvious reasons versus trying to make a highly dilute solution and having to weigh out tiny fractions of Baking soda.

This means more error.

So do yourselves a favor, make a high KH ref stock solution, get a decent graduated cylinder, measure out the dilutions by 10% then another 10% etc.
This will give you more accuracy as will making 1 liter vs 100mls, DI water and baking soda are both cheap, so volume is much less an issue.

Also, when you make a solution, make enough to share with friends and put in sealable bottles that prevent evaporation completely.
If you do this right once, you will not have to do it except once every 2-5 years etc.


Regards,
Tom Barr

Okay Tom, thanks. I'll do as you suggested (cooking baking soda prior and greater/more amount/volume of soda and distilled water).

I've measured as precisely as possible. I will report back if calculation and measurement match better afterwards.

Regards,
Detlef

Main thing is doing the dilutions from high to low to get an accurate amount.

Another issue is how you calculate alkalinity, use the RC calculator, I think it's more accurate and correct than the others.

Regards,
Tom Barr

Sorry for some stupid questions:

Tom, what exactly do you mean by cooking the baking soda prior to mixing the solution? Filling the dry salt in a pot and cook it on a hot plate or oven without any other additions? And for how long?
The reason is to rid NaHCO3 from water and CO2, right?

Thank you,
Detlef

Yes and yes.
About 300-400F for an hour ought to drive off anything there.
Baking soda will attrach water vapor, absorb odors etc.

Read the KH ref link here for the Reef hobby:

Chemistry and the Aquarium - Randy Holmes-Farley

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com

Chemistry and the Aquarium

Here's another KH calculator

CNYKOI - Alkalinity (KH) calculator

so 94 mg in 1 gallon of water = 17.86ppm of KH.
For 4 KH, you'd need to add 376 mg of baking soda to make a ref solution of 4KH.

Now if you made a ref solution of say 40 KH, then you'd gain a significant figure when you did a dilution assuming you have an accurate volumetric flask etc to measure the dilution water.

I have a scale that will go to 0.0001. Not many do, I have one at home that's good to 0.001 ...few have these in the hobby.
So I can get pretty close............

Closer than anyone else for the most part with the pH and KH measures and response times.

I have a very significant reason for such accuracy and detection.
Most think I'm just being obsessive, perhaps.........but I want to know how much variation in CO2 will induce algae and BBA etc.

In order to know this, I need to have very accurate CO2 measurements at low ranges to show that there is a strong relationship between water changes and BBa in non CO2 addition plant tanks.

Regards,
Tom Barr

Tom, thanks again for explanations and link list.

I very much appreciate you pushing the accuracy of CO2 measurements in order to get a better understanding of varying/different C02 levels and algae inducement. Can't wait to see the results!

As for me being a hobbyist I'll keep on using a "precise" ref KH for drop checkers (thanks Vaughn for your ideas) and a reasonable pH table.

Best regards,
Detlef

Hey Tom,

Are you selling any KH reference solution?

No, but I think Greg might, he's sell the dry pre weighed baking soda that you'd just fill with DI water to a certain level, or small bottles of it.

The pH probe makers should do this really.

That's why I'm bugging them.
But a smart person would give it a try right now.

I do not like selling material products really.
I'd rather detail out how to and then let others do it.
My goal is not money although I do charge for the BarrReport subscription(I do not intend to lose money ), the infomation is worth more than the products folks might sell.

It's improving the methods and advancement in the hobby that was chock full of issues whern I got in and it's still a long way off.

But each step is a step towards a better understanding rather than wheel spinning or heading off in the wrong direction hopefully.

It's the evolution of the hobby itself.
My goals are much more idealistic perhaps?
I make $ doing other things.
This is for fun.

Both myself and Greg Watson are both this way.
This is a hobby to both of us and we do it to help the hobby, not lose more $, help folks etc.

I do have some items I might eventually sell and slap my name on.
But anyone can make this themselves.
The items I have in mind require more expertise and skills and are far from a DIY project. Otherwise, anyone anywhere can do a KH solution.

Hard to compete and the time factor does not offer me much $$ selling KH product direct to anyone.

Regards,
Tom Barr

Looks like you got it figured out