DIY Trace recipe calculation (please verify)

[zachtos]

Example: Barium Supplement
BaCl2 (2H2O)
1. I find molecular weight (244 gram per mole), do this by adding molecular weight of each element (multiply as needed)
2. now take the weight of the primary trace element and divide by the sum of the molecular weight to find percentage weight ( 137 / 244) = 56.2% barium by weight
3. now take a sample solution, in this example I weigh out 5 grams of Barium Chloride. I divide by weight of 500ml of RO water which is 500 grams, so grams cancel. 5/500 = 0.01 * 56.2% barium by weight is 5614 ppm (mulitply result by 1 million to get to ppm)
4. I found concentration too high, so diluting by only putting 10ml / 200ml (10ml solution in 200ml water, so 0.05 * 5614 = 280ppm.
5. Now we have 210ml of Barium trace element solution that is 280 ppm concentration, so how much do we need to buff our tank?
6. in my example, I needed to calculate how many ml to bump 300 gallons of water up by 0.1microgram/L.
280 ppm * Xml = 0.1ug/L * 300 gallon * 3.785 L / gallon
liters and gallons cancel out, and left with microgram, which is equal to microliters
now divide both sides by 280ppm concentration
0.1uL /280ppm * 300 * 3.75 = 0.4 = xmL
*** above I think maybe I have a mistake? uL/ppm, do I need to convert to L then to mL, so maybe multiply the result by 1000??? Am I even close on this calculation?

 

[Randy Holmes-Farley]

I would never add barium to a reef. It is no known biological role in any organism.

 

[zachtos]

Thanks, but I was more interested in example calculations, I have about 12 other trace elements I can exchange for calculations results.

 

[Randy Holmes-Farley]

OK.

Step 4 should be 10 mL into 200 mL total volume (10 stock solution + 180 mL RO/DI).

A supplement that is 280 ppm is 280 ug/mL

Your tank is 300 gallons = 1136 L.

Your target is 0.1 ug/L.

If you add [0.1 ug/l x 1136 L ]/280 ug/mL = 0.4 mL , you will reach your target. Which is what you got.

 

[zachtos]

Before and after test reports, after I dosed all DIY:
Flourid = corrected
Boron = corrected
Molybdenum = corrected
Barium = dropped? maybe tank uses it too fast, bad calculation, or precipitates too fast?
Iodine = no change, or not able to test ICP, or tank uses it too fast?
Iron = no change, or not able to test ICP, or tank uses it too fast?
Manganese = no change, or not able to test ICP, or tank uses it too fast?

New
Vanadium = dropping 0.31uG/L per 5-6 weeks (if ICP accurate)
Zinc = dropping 0.65uG/L per 5-6 weeks (if ICP accurate)

*replenish by Brightwell aquatics (250ml in a month) - this **** does nothing, waste of money or so diluted it does nothing. Bought it to try to bring up the oddball items like silver, selenium, copper, cobalt, chromium etc. Probably don't need those anyway from what I read. Just Iron and Iodine seem to be important for weekly dosing.

*** Question - Barium you said is not important, but I dosed it based on those calcs, and so no change. Does my tank actually use it up, did it precipitate out, or maybe a mistake?
** same question applies to Iodine, Iron, Manganese. I'm curious if that means my demand is high, or solutions I may have created were wrong or possible they precipitate out of the solution etc?
** I have heard ICP is not always reliable for some minor elements like iron, iodine. Is this true?

 

[zachtos]

I have created a google shared doc that others can use to create all of their own supplements and how to dose them. I have went 2 years with no water change now in my 300G SPS and it's doing quite well.
ICP DIY supplements (zachtos)

 

[akaimal]

I have created a google shared doc that others can use to create all of their own supplements and how to dose them. I have went 2 years with no water change now in my 300G SPS and it's doing quite well.
ICP DIY supplements (zachtos)

This is awesome!! Thanks for sharing your knowledge.

 

[chiyennh9293]

I have created a google shared doc that others can use to create all of their own supplements and how to dose them. I have went 2 years with no water change now in my 300G SPS and it's doing quite well.
ICP DIY supplements (zachtos)

Hello. Let me ask you a question. In your spreadsheet, the column “goal mg/L” is the daily dose of the solution you add, correct.

 

[zachtos]

Hello. Let me ask you a question. In your spreadsheet, the column “goal mg/L” is the daily dose of the solution you add, correct.

The blue column is just the amount to raise it from X to Y. So I use it for correction after an ICP report, but those ended up being my average weekly doses in my sample. My tank is taking a downturn, so all the numbers are very low on dosing right now, but I believe that is caused by my change over of T5 to LED. Wish I didn't do that, LED so pretty but so difficult vs. T5.

 

[chiyennh9293]

Oh. you add weekly or daily. thank you very much.

 

[chiyennh9293]

The blue column is just the amount to raise it from X to Y. So I use it for correction after an ICP report, but those ended up being my average weekly doses in my sample. My tank is taking a downturn, so all the numbers are very low on dosing right now, but I believe that is caused by my change over of T5 to LED. Wish I didn't do that, LED so pretty but so difficult vs. T5.

Oh. you add weekly or daily. thank you very much.

 

[wmb0003]

Oh. you add weekly or daily. thank you very much.

The values on his spreadsheet are 1 time doses to get to the level you want.

You should send off an ICP test and see which elements are low and then dose only what is needed.

Some elements deplete quicker than others, after a few ICPs, you could probably figure out how much of each element your system consumes and then dose based on that info. But I would still send off the occasional ICP to ensure you do not overdose anything.

 

[MikeTheNewbie]

Example: Barium Supplement
BaCl2 (2H2O)
1. I find molecular weight (244 gram per mole), do this by adding molecular weight of each element (multiply as needed)
2. now take the weight of the primary trace element and divide by the sum of the molecular weight to find percentage weight ( 137 / 244) = 56.2% barium by weight
3. now take a sample solution, in this example I weigh out 5 grams of Barium Chloride. I divide by weight of 500ml of RO water which is 500 grams, so grams cancel. 5/500 = 0.01 * 56.2% barium by weight is 5614 ppm (mulitply result by 1 million to get to ppm)
4. I found concentration too high, so diluting by only putting 10ml / 200ml (10ml solution in 200ml water, so 0.05 * 5614 = 280ppm.
5. Now we have 210ml of Barium trace element solution that is 280 ppm concentration, so how much do we need to buff our tank?
6. in my example, I needed to calculate how many ml to bump 300 gallons of water up by 0.1microgram/L.
280 ppm * Xml = 0.1ug/L * 300 gallon * 3.785 L / gallon
liters and gallons cancel out, and left with microgram, which is equal to microliters
now divide both sides by 280ppm concentration
0.1uL /280ppm * 300 * 3.75 = 0.4 = xmL
*** above I think maybe I have a mistake? uL/ppm, do I need to convert to L then to mL, so maybe multiply the result by 1000??? Am I even close on this calculation?

Hi @zachtos and @Randy Holmes-Farley when calculating the mix of compound (solute) to RO water (solvent) shouldn't we divide the compound by the total weight of the solution instead of just the weight of the solvent?
E.g. In step 3 we have 5 grams of Barium chloride and mix it with 500g of RO water I'm thinking that the calculation should be 5 / 505 * 0.562208665 * 1,000,000 = 5,566.422425 ppm (or mg/L)
instead of 5 / 500 * 0.562208665 * 1,000,000 = 5,622.08665 ppm (or mg/L)
The 505 comes from the addition of the 5g of Barium chloride + 500g of RO water.
If that is not correct, could you help with an example? I'm a bit confused. Thanks!

 

[Randy Holmes-Farley]

Hi @zachtos and @Randy Holmes-Farley when calculating the mix of compound (solute) to RO water (solvent) shouldn't we divide the compound by the total weight of the solution instead of just the weight of the solvent?
E.g. In step 3 we have 5 grams of Barium chloride and mix it with 500g of RO water I'm thinking that the calculation should be 5 / 505 * 0.562208665 * 1,000,000 = 5,566.422425 ppm (or mg/L)
instead of 5 / 500 * 0.562208665 * 1,000,000 = 5,622.08665 ppm (or mg/L)
The 505 comes from the addition of the 5g of Barium chloride + 500g of RO water.
If that is not correct, could you help with an example? I'm a bit confused. Thanks!

You are certainly correct that if you want to make a solution that is 5 g/kg or 0.5 wt %, you add 5 grams of solid to 995 g of water.

But there are several reasons that this level of accuracy is not always needed.

First, unless you make quite concentrated solutions (which is typically inappropriate for a trace element additive), the solute is a minor contributor to weight. If you are off by 5% in dosing manganese, is anyone concerned? Our measurements of concentrations and tank water volume, etc., are not likely that accurate to begin with.

Second, most people dose by volume anyway, not mass. If you mix a small amount solid into a large amount of water, the volume may not increase much. In some cases it declines The density increases, typically, partly offsetting the mass increase.

Finally, most trace element dosing is finalized by trial and error. Slight differences in the dosing solution just become one of many factors in determining a final dose that is optimal.

So yes, one needs to account for these things, but if you do not, the errors are likely insignificant.

 

[MikeTheNewbie]

Awesome, thank you so much Randy!
I'm doing some calculations for elements I bought and I'm getting different numbers so I'm going back to recheck that my formulas work. This was the first difference I found so I thought this was the cause. I think I have another error, will keep looking.
Thanks again!

 

[Randy Holmes-Farley]

Awesome, thank you so much Randy!
I'm doing some calculations for elements I bought and I'm getting different numbers so I'm going back to recheck that my formulas work. This was the first difference I found so I thought this was the cause. I think I have another error, will keep looking.
Thanks again!

You're welcome.

Feel free to post them here if you get stuck.

 

[MikeTheNewbie]

Hi @Randy Holmes-Farley , I'll take you up on your offer for help with the chemistry calculations.
I'm looking at a document called "Mack's Reef Dealing with Dinos" where they recommend dosing waterglass (41% liquid sodium silicate) to induce a diatom bloom and outcompete dinos.
They recommend 0.1 ml per 15 gallons to increase silicate by 1ppm.
I bought this product that is described as 41% Na₂SiO₂ and 59% H₂O.
According to my possibly faulty calculations (I'm an engineer, not a Chemist) the silicate concentration of that solution is 0.4ppm, not 0.1ppm as described in the document

Here is my logic:

• A) Molecular weight of Silicate (SiO₂) = atomic mass of Si + O * 2 = 28.0855+15.9994*2 = 60.0843 g/mol
• B) Molecular weight of Sodium Silicate (Na₂SiO₂) = atomic mass of Na * 2 + Si + O * 2 = 22.9897*2+28.0855+15.9994*2 = 106.0637 g/mol
• C) Product concentration is 0.41 (41% Sodium Silicate + 59% distilled water)
• D) To get the ratio of Silicate by weight of the waterglass product I bought I divide A / B * C = 60.0843 / 106.0637 * 0.41 = 0.2322 (meaning that there is %23.22 of silicate in this product
• Now to get the ppm of silicate when dosing 0.1ml of product to 15 gallons of water I'm doing:
• E) 0.1ml of product
• F) 15 US gal water = 56,781.2 g (assume 1 ml = 1 gram)
• product weight / (product weight + water weight) * ratio of silicate in product * 1,000,000 = E / (E+F) * D * 1,000,000 = 0.1g / (0.1g + 56,781.2 g) * 0.2322 * 1,000,000 = 0.4089ppm

I hope you can help me see if I made a mistake. I'm enjoying remembering chemistry from my high school days (long time ago) and I'm trying to ensure I'm getting it right. Not trying to question the paper I got the information from at all. I'm grateful to them for publishing it as a guideline and to you for your coaching.

I saw that the vendor of the project shows silicate as SiO3 in their MSDS instead of SiO2 that they show on their product page but when I do the calculations with SiO3 I still get a very different concentration (0.35 ppm) so I think that is not the issue.

Thank you very much for the help!

 

[Randy Holmes-Farley]

A few comments.

It's not correct to assume it is Na2SIO2. Silicate is not SiO2 exactly. Wikipedia describes the forms that can be present.

The density is well above 1 g/mL.

I show the calculations in an article below: 1.3 grams (0.96 mL) added to 100 gallons boosts SiO2 by about 1 ppm.

You specifically asked about 0.1 mL (which equals ~ 0.135 g) in 15 gallons
So 0.1 mL in 15 gallons would boost SiO2 by about 0.7 ppm.

Silica In Reef Aquariums

Why would I recommend dosing silica? Largely because creatures in our tanks use it, the concentrations in our tanks (at least in mine) are below natural levels, and the sponges, mollusks, and diatoms may not be getting enough to thrive.

reefs.com

Here’s how to determine dosing amounts. I’ll assume that you want 17 uM (1 ppm SiO2) dosing, and you can scale from there. If the concentration of the supplement is 29% silica by weight (41° Baume), then it is 290,000 ppm silica. To get to 1 ppm silica, you then need to dilute by 290,000 fold. If you add 1.3 grams of this supplement (0.96 mL) to a tank with 100 gallons (378,500 mL), then the final concentration will be about 17 uM (1 ppm SiO2). I’d disperse the concentrated silicate solution into some fresh water before adding it to the tank, and then add it to a high flow area. Because the pH is high, you likely will see some cloudiness that is mostly magnesium hydroxide. The magnesium hydroxide will dissolve without a problem, but to be safe, add the supplement in a high flow area.

 

[MikeTheNewbie]

Thank you so much Randy, I didn't realize you had an article on silicates. I'll study it this afternoon and then I'll try to do the math to see where I had the mistake. As you say, the density must be a big part of my error. Thanks again for sharing the wisdom!

 

[Gman181]

I have created a google shared doc that others can use to create all of their own supplements and how to dose them. I have went 2 years with no water change now in my 300G SPS and it's doing quite well.
ICP DIY supplements (zachtos)

Hi Zachtos
I really appreciate your document I am going to try to use your guide on my system it’s 2000l and the little bottles from triton don’t cut it and I would rather spend the money on corals. I am not a chemist but not stupid either. Before I start is there a updated version or any tips? Many thanks George