Why different powder mineral brands have such a different concentration when mixed with water. Need help from Chemist.

[ak21]

Need help from reef chemist. I read about anhydrous salts and hydrated salts but still bit confused. Im not suggesting whats good or better but like to understand so i can make smart choice when i decide to buy stuff.

Example is magnesium supplement from seachem and continuum.
Data is taken from there website.

to increase 100pm in 250 gallon tank
Seachem requires 1187grams

(example, if you want to raise magnesium by 10 mg/L in a 200 liter tank, then you would add (200x10)/80=25 g into the top-off water.)

continuum claims 225grams

( Example: if you have a 20 gallon tank and you want to raise the level by 25 mg/l (ppm) with the entire dose, you would multiply 20 x .009 x 25 which equals 4.5 grams or about 2 teaspoons of Reef•Basis Magnesium.)


Same thing for strontium as well to raise 8 to 10pm in 250 gallons
Seachem requires 66grams
(For example, if you want to raise strontium by 6 mg/L in a 200 L aquarium, then you would add (200x6)/30=40 g into the top-off water.)

continuum claims 3.7grams
(Example: if you have a 20 gallon tank and you want to raise the level by 3 mg/l (ppm) with the entire dose, you would multiply 20 x .0074 x 3 which equals .44 grams )

Look how much difference is the weight of supplement. I need to know why. Also are the claims of continuum right? or its fake claim, cause difference is huge. I compared other brands as well but they were similar to seachem weight.

 

[Dread Pirate Dave]

Welcome to R2R!

I am not a chemist though so not much help from me there.

 

[Randy Holmes-Farley]

Need help from reef chemist. I read about anhydrous salts and hydrated salts but still bit confused. Im not suggesting whats good or better but like to understand so i can make smart choice when i decide to buy stuff.

Example is magnesium supplement from seachem and continuum.
Data is taken from there website.

to increase 100pm in 250 gallon tank
Seachem requires 1187grams

(example, if you want to raise magnesium by 10 mg/L in a 200 liter tank, then you would add (200x10)/80=25 g into the top-off water.)

continuum claims 225grams

( Example: if you have a 20 gallon tank and you want to raise the level by 25 mg/l (ppm) with the entire dose, you would multiply 20 x .009 x 25 which equals 4.5 grams or about 2 teaspoons of Reef•Basis Magnesium.)


Same thing for strontium as well to raise 8 to 10pm in 250 gallons
Seachem requires 66grams
(For example, if you want to raise strontium by 6 mg/L in a 200 L aquarium, then you would add (200x6)/30=40 g into the top-off water.)

continuum claims 3.7grams
(Example: if you have a 20 gallon tank and you want to raise the level by 3 mg/l (ppm) with the entire dose, you would multiply 20 x .0074 x 3 which equals .44 grams )

Look how much difference is the weight of supplement. I need to know why. Also are the claims of continuum right? or its fake claim, cause difference is huge. I compared other brands as well but they were similar to seachem weight.

I do not have time to work through the numbers at the moment, but they do not appear correct for hydrated vs anhydrous, which is about a factor of 2 in potency of the solid. Typical solid magnesium sources have a huge amount of water in the solid crystals and are only about 11% magnesium by weight (the rest is not all water, the sulfate and chloride are also there).

You can use this calculator to compare any product claims to the dry solid magnesium chloride and sulfate sources listed.

Reef Chemistry Calculator

reef.diesyst.com

Anhydrous solids are neither better nor worse to use, and all can be made about as potent as you want in solution, but they will use substantially less solid to reach the same potency.

 

[irischan]

Checked the product website on Seachem. It states the ingredient has 80mg magnesium per 1g, which is 8% purity.

Whilst on Continuum, it states guaranteed analysis has 43% purity.

By looking at the purity difference, the Cotinuum has 43÷8=5.3. This means the Cotinnum has 5 times content.

So I think this makes their difference in the dosage recipe.

 

[irischan]

By the way, I checked Brightwell magnesium also. It stated product guaranteed analysis as magnesium 24%.

Going through its dosage calculation, I think the dosage calculation among these three companies make sense.

 

[Randy Holmes-Farley]

Checked the product website on Seachem. It states the ingredient has 80mg magnesium per 1g, which is 8% purity.

Whilst on Continuum, it states guaranteed analysis has 43% purity.

By looking at the purity difference, the Cotinuum has 43÷8=5.3. This means the Cotinnum has 5 times content.

So I think this makes their difference in the dosage recipe.

There is no magnesium compound we dose that is 43% magnesium. Brightwell made a serious math mistake years ago to get a value like that, and they changed it when pointed out. Continuum may be making a similar serious mistake.

Anhydrous magnesium chloride is 25.5% magnesium by weight.

Anhydrous magnesium sulfate is 20.2% magnesium by weight.

Since many products are a combination of these two ingredients, I suspect some people added the percentages together, which obviously gives faulty numbers.

 

[Randy Holmes-Farley]

FWIW, they literally and incorrectly claim on their web site that being anhydrous gives them 4x potency. That is simply incorrect. It is 2x.

 

[irischan]

Then there is significant question on the products' so-called "guaranteed analysis".

 

[Randy Holmes-Farley]

Then there is significant question on the products' so-called "guaranteed analysis".

Where do you see it written?

 

[Randy Holmes-Farley]

I only see the incorrect 4x here:

Continuum Aquatics | reef•basis magnesium

 

[irischan]

Where do you see it written?

It is on product label.

 

[Randy Holmes-Farley]

It is on product label.

Ok, well, it’s not correct for any material suitable as a magnesium only supplement in a reef tank.

The closest thing would be magnesium hydroxide. It is 41.7% magnesium by weight, but for each 20 ppm boost to magnesium, it would add 4.6 dKH of alkalinity. It also does not fit the heat generating comments or the anhydrous description in their site.

There are no other counter ions that would be suitable for reef use at all.

 

[KStatefan]

This seems to come up regularly that the instructions/statements are incorrect in basic chemistry, How do customers trust any thing they say if the basic stuff is incorrect?

 

[ak21]

Also just did more research Brightwell and and Continuum are same companies just different branding.
People trusting them when they dose. Atleast they can give bit of time on what they put on website or on instructions.

 

[Randy Holmes-Farley]

Also just did more research Brightwell and and Continuum are same companies just different branding.
People trusting them when they dose. Atleast they can give bit of time on what they put on website or on instructions.

Well, that's interesting since Brightwell had the same issue until I corrected them in 2015, but apparently they did not tell their partner.