Question regarding Randy's recipe

[shaidas]

I have been using Randy's recipe for a while like most other folks. Recently I bought a KH Guardian and their recommended alk sol calls for 65 grams of raw Sodium Bicarb which they reckon creates a solution wherein 1 ml will raise the alk of 1L of water by 2.17 dKH . Using the article here http://reefkeeping.com/issues/2006-02/rhf/index.php , to me it seems 79 grams of raw Sodium Bircarb should be raising the alk by .70 dKH. I must be getting it wrong but I don't quite understand how.

As per the article 297 gms creates a 1 gallon (3785.41ml) of solution containing 2660dKH. Which means every ml of that solution contains 2660/3785.41 = .70 dKH . Now if we scale the solution down to 1L or 1000mL , we need 297/3785.41 x 1000 = 79 grams of bicarb soda.

So if we add 79 grams of raw bicarb soda to 1 L of water, do we end up with a solution where 1 ml will raise the dKH of 1L by .70 dKH or am I way off base here ?

 

[Flippers4pups]

I can't answer the ratio questions, but I have made my solutions based on Randy's recipes and use this calculator to dose them:

Reef Chemistry Calculator

 

[JimWelsh]

You are misinterpreting part of the article in a significant way: The "2660 dKH" is per liter, not per gallon (he says right before that, "950 meq/L of alkalinity" -- note the "/L" -- 950 meq = 950 * 2.8 dKH = 2660 dKH), so you are erring when you divied by 3785.41. Just divide by 1000 instead.

EDIT: Oh, BTW, the KH Guardian math works out, too.

 

[shaidas]

Thank you for trying to help. I am aware of these calculators online but they do not allow 1 litre /1 dKH calculations. I am trying to ascertain that in these solutions, how much does a ml impact the alk of 1 L of water by taking Randy's article as a base. KH Guardian has been around for a while so their calculations are most likely correct but I am just wondering why then do I arrive at the above result from Randy's recipe ? Where am I going wrong.

 

[shaidas]

You are misinterpreting part of the article in a significant way: The "2660 dKH" is per liter, not per gallon (he says right before that, "950 meq/L of alkalinity" -- note the "/L" -- 950 meq = 950 * 2.8 dKH = 2660 dKH), so you are erring when you divied by 3785.41. Just divide by 1000 instead.

EDIT: Oh, BTW, the KH Guardian math works out, too.

Nah bud I think you are mistaken .. meq/L is the unit of measurement , milliequivalents per litre . The base solution is using a gallon of water and contains alkalinity equivalent to 950 meq/L OR 2660 dKH

http://reefkeeping.com/issues/2005-08/rhf/#:~:text=%EF%BF%BD%20The%20units%20of%20alkalinity,50%20ppm%20CaCO3%20equivalents

.

 

[JimWelsh]

Randy's recipes have been around a lot longer than the KH Guardian! LOL! Did you read my response? I answered your question, "Where am I going wrong?"

 

[JimWelsh]

Nah bud I think you are mistaken

Then I'll stop wasting your time.

 

[shaidas]

Randy's recipes have been around a lot longer than the KH Guardian! LOL! Did you read my response? I answered your question, "Where am I going wrong?"

If it were to be 1 L like you are suggesting that would imply 297 grams creates a solution of 1 L with 2660 dKH which yields 27dKH per ml for a litre of water which in turn implies 1 gram in 1 L results in 8.9 dKH!!

 

[Flippers4pups]

#reefsquad

 

[JimWelsh]

If it were to be 1 L like you are suggesting that would imply 297 grams creates a solution of 1 L with 2660 dKH which yields 27dKH per ml for a litre of water which in turn implies 1 gram in 1 L results in 8.9 dKH!!

I already answered your question, but, then, I'm just some rando on the Internet, and I probably don't know what I'm talking about when it comes to anything having to do with alkalinity, so, you just go ahead and do you. I'm not in an arguing mood.

 

[shaidas]

I already answered your question, but, then, I'm just some rando on the Internet, and I probably don't know what I'm talking about when it comes to anything having to do with alkalinity, so, you just go ahead and do you. I'm not in an arguing mood.

Woah ..mate not trying to argue or offend here just trying to understand..I am very thankful for your reply

 

[Flippers4pups]

Let's keep the discussion civil.

 

[shaidas]

Ok I took a look at the code in the online calc.. here are the magic numbers in case anyone is interested Sodium Bicarb .318028256 gr= 1meq/lt in 1 gal and Baked Sodium Bicarb .200617872 gr = 1meq/lt in 1 gal . This explains the KH Guardian calculation though I still dont know how these figures were reached and why my calculation is going wrong.

Two important things to consider here, firstly to make the statement 1ml will raise the dKH by x in 1L , you need to assume a tank of 1000 L so this statement is inaccurate because increase is in respect of tank volume it cannot be exclusive. Secondly the online calculator is converting all L to gallons and dKH/ppm to meqL so there is a variance of around 3 grams in the conversion and rounding off not the end of the worl but interesting to note.

Still keen to understand how these per gram figures were arrived at and how my calculation is going wrong if anyone has any ideas.

 

[JimWelsh]

if anyone has any ideas.

I'm going to try to explain this one more time. Randy's recipe calls for 297 grams of baking soda in 1 gallon. 297 grams of baking soda in 1 gallon of water provides 297 / 84.007 * 1000 = 3535 meq = 3535 * 2.8 = 9899 dKH of total of alkalinity in that one gallon. Now, that means that there is 3535 / 3.8754 = 934 meq/L = 2615 dKH/L of alkalinity. Now, I know that these numbers differ slightly from Randy's calculations, and I have heretofore deferred to Randy's number, but these are the numbers that I get, based on the well-known numbers for the molecular weight of sodium bicarbonate, which is what these calculations should be based upon, and my current argument is not with Randy. So, as I said in my original answer, the "2660 dKH" number you cited in your original question is *PER LITER* and not *PER GALLON*, even though the number I come up with is more like "2615 dKH" *PER LITER*. To restate: Randy's recipe specifies 9899 dKH *PER GALLON*, which is 2615 dKH *PER LITER*. Please re-read my original response. Please take the number of grams of the substance, divided by the molecular weight of the substance, divided by the number of liters in the solution, in order to determine the concentration in moles per liter that the final solution will have. It's really rather simple math.

 

[Rick.45cal]

Jim answered your question correctly, You aren’t keeping your units of measurement the same in your formula. You’re dividing the dKH/L with how many ml/gallon.

You either need to divide the dKH/Liter with the number of ml per Liter (1000) or you need to compute the dKH/gallon (10,069.19 dKH/gallon) and divide that by the number of ml/gallon (3785.41 ml/gallon). You have to maintain the same units in the formula to arrive at the correct answer.

2660 dKH/L / 1000 ml/L = 2.66 dKH/ml.

10,069.19 dKH/gallon / 3785.41 ml/gallon = 2.66 dKH/ml

 

[Littleii5278]

65 gram baking soda melted to a 1000 liter tank will raise that tank kh by 2.17 base in Randy’s calculator.

When u melt 65 gram Of baking soda to 1000ml which is 1 liter. Isn’t each ml contain 0.065 gram ? Isn’t this 0.065 gram added to 1 liter water raised 2.17 kh which on the other hand equilibrium to melting 65 gram to a 1000 liter tank and raise 2.17 kh.

so both Randy calculator and KHG manual are correct

 

[shaidas]

I still dont understand your logic Jim Welsh but Rick.45 Cal explains the issue with my original calc. I am not the sharpest tool in the shed as is obvious :-D . Littleii5278, I never said Randy's was wrong or KHG was wrong, I started by saying I am wrong, just trying to figure out how !! So basically the first half of my calculation was wrong, because I did not convert the gallons to Litres. 79 grams in 1L leads to 2.66 dKH and that makes sense now as compared to KHG's numbers. Now anyone got any ideas as to how the magic numbers being used were arrived at Sodium Bicarb .318028256 gr= 1meq/lt in 1 gal and Baked Sodium Bicarb .200617872 gr = 1meq/lt in 1 gal ? Thanks for all the replies guys ..much appreciated

 

[Randy Holmes-Farley Verified Community Expert]

I know folks here probably understand this, but just to clarify, my recipe article:

http://reefkeeping.com/issues/2006-02/rhf/index.php

says

" Dissolve 297 grams of baking soda (about 1 1/8 cups) in enough water to make 1 gallon total. This dissolution may require a fair amount of mixing. Warming it speeds dissolution. This solution will contain about 950 meq/L of alkalinity (2660 dKH). "

Both of those units of measure of alkalinity are correct exactly as written.

Importantly, there is NO unit of volume missing from the dKH unit. It already contains a volume component in "dKH", where 1 dKH is the alkalinity provided by 17.86 milligrams of calcium carbonate per litre . The use of a factor of a thousand comes because the OP suggests putting 1 mL into a liter.

Thus adding 1 mL into 999 mL of RO/DI boosts the alkalinity by 2660/1000 = 2.66 dKH.

We can verify article numbers as follows:

297 grams of sodium bicarbonate (molecular weight = 84 g/mole) contains 3.54 moles of bicarbonate.

That 3.53 moles of bicarbonate is 3,530 milliequivalents of alkalinity.

One gallon is 3.78 L, so the solution contains 3,530 milliequivalents per 3.78 L = 934 meq/L (rounding issues are likely how i got the 0.95 in the article).

The conversion from meq/L to dKH is a factor of 2.8, so the 0.94 meq/L is equivalent to 2615 dKH.

If you put 1 mL of this fluid into a liter of water, the alk rises by 2.6 dKH.

 

[Randy Holmes-Farley Verified Community Expert]

Now anyone got any ideas as to how the magic numbers being used were arrived at Sodium Bicarb .318028256 gr= 1meq/lt in 1 gal and Baked Sodium Bicarb .200617872 gr = 1meq/lt in 1 gal ? Thanks for all the replies guys ..much appreciated

I'm not sure I understand that question, but recipe#1 uses exactly twice as much sodium bicarbonate per unit of volume so gets twice the alkalintiy. The baking has no effect on alk, but you measure the mass before baking. If you measure the mass after baking, you are adding less of it since it lost mass during baking.

 

[shaidas]

Thanks for the response Randy, yes I understand that bit now. The question I was asking was for the calculator available here http://reef.diesyst.com/chemcalc/chemcalc.html , it is not referring to your recipes instead when a user select Sodium Bicarbonate it is using these numbers .318028256 gr raises 1meq/lt in 1 gal . Your recipes are a separate selectable option.