Quick Question on Alk Solution Strength

[LobsterOfJustice]

I mix 3.25 cups of baked baking soda in enough RODI water to make 1 gallon total volume.

1 mL of this solution added to 1 L tank water raises the dKH how much?

Background: this is for my alkalinity monitor and I would like to use the same alk solution I mix up for regular dosing instead of their solution, but I need to tell the unit the strength of my solution for it to know how much to dose.

 

[JimWelsh]

If you had said how much mass instead of how much volume of sodium carbonate you used, it would be possible to answer accurately. Volume is not a good way to measure substances with any real accuracy.

 

[Martin Kuhn]

I agree to Jim

What about if you again take a cup and measure its weight. (W/O the cup itself). Then we could tell you

 

[LobsterOfJustice]

Every two part recipe talks in terms of cups of ingredients, I’m sure 99.9% of people measure volume of components and not weight. There are online calculators that tell you how much of Randy’s two part to add to raise your tank by a certain amount, and Randy’s recipe is measured in cups, so I’m sure there is a simple algebra problem that can take that formula and answer my question.

At this point, easier to just measure the KH of 1L of water, add 1 mL of solution, and then test it again, so I will just do that.

 

[Randy Holmes-Farley Verified Community Expert]

The volume measurements in my recipes calls for measuring the baking soda before baking, not after. The volume will decline on baking, but without knowing more info (including whether it is fully converted into sodium carbonate), volume measurement of it is only a rough guide.

If you think you fully converted it, you can use this calculator to determine the alk is the dosing solution, using the entry for sodium carbonate and it's estimate of how fluffy the material might be (which is imperfect).

Reef Chemistry Calculator
http://reef.diesyst.com/chemcalc/chem_calc3.html

For example, use 1 gallon as the volume and 1 dKH for the start alk. If you enter 3000 dKH for the final alk, you get 48 teaspoons, which s 1 cup.

So 1 cup in one gallon is about 3000 dKH.