Using calcium carbonate as a flocculant

[Dan_P]

Phosphate binding to aragonite is, of course, surface area dependent, but it has been published in the scientific literature, and measured by jda here on rocks.

Adsorption of Phosphate on Calcium Carbonate

www.aoml.noaa.gov

I am indeed aware of this from years ago when you provided this link to on another forum. My point is that as a flocculant, not much mass is being added. The amount of phosphate reduction in the aquarium would seem to be of little consequence. Ditto DOC reduction.

 

[Randy Holmes-Farley]

I am indeed aware of this from years ago when you provided this link to on another forum. My point is that as a flocculant, not much mass is being added. The amount of phosphate reduction in the aquarium would seem to be of little consequence. Ditto DOC reduction.

I haven’t worked through a surface area calculation to know, but that might be true.

 

[Dan_P]

I haven’t worked through a surface area calculation to know, but that might be true.

OK, if you don’t run the calculation or you do and I want to double check it I could measure the PO4 adsorption per gram of powdered calcium carbonate. The DOC adsorption might be obtained with a before and after TritonNDOC test, though not sure that would be money well spent.

 

[Randy Holmes-Farley]

Without knowing either the particle size or the surface roughness of the materials used, I think it is impossible to calculate anything useful.

That said, this paper tests some form of calcium carboante for organic binding from fresh water with a little salt in it, and they find this result:

https://doi.org/10.1016/S0927-7757(01)00760-9

"
. The maximum surface density of humic acid increased from 20 mg g−1 at pH 9.5 (open circles) to 120 mg g−1 at pH 7.5 (filled circles). For both pH values, a plateau was observed at high equilibrium concentrations suggesting monolayer coverage on the calcium carbonate surface."

At 5 ppm or humic acid and at pH 7.5, they get about 10 mg humic acid absorbed per gram of calcium carbonate.

 

[Dan_P]

Without knowing either the particle size or the surface roughness of the materials used, I think it is impossible to calculate anything useful.

That said, this paper tests some form of calcium carboante for organic binding from fresh water with a little salt in it, and they find this result:

https://doi.org/10.1016/S0927-7757(01)00760-9

"
. The maximum surface density of humic acid increased from 20 mg g−1 at pH 9.5 (open circles) to 120 mg g−1 at pH 7.5 (filled circles). For both pH values, a plateau was observed at high equilibrium concentrations suggesting monolayer coverage on the calcium carbonate surface."

At 5 ppm or humic acid and at pH 7.5, they get about 10 mg humic acid absorbed per gram of calcium carbonate.

This means that the recommended dose of one tablespoon or 2.7 g of calcium carbonate per 50 gallons or about 200 liters translates to ~ 30 mg humic acid removed from a total of 1000 mg (200 L @ 5 ppm). If my math is correct, calcium carbonate should not be expected to impact DOC.

 

[ctopherl]

I cannot see it promoting bacteria more than when the organics are dissolved, but as folks note, it does help clear the water of organics and phosphate.

Is food grade safe to dose? I cannot easily find Pharma grade

 

[Rmckoy]

Is food grade safe to dose? I cannot easily find Pharma grade

I buy the powder from the health food store .

 

[ctopherl]

I buy the powder from the health food store .

Is yours Pharma or food grade?

 

[minus9]

Is food grade safe to dose? I cannot easily find Pharma grade

Just buy it from Amazon. Food grade at 97% is all you need.

 

[Rmckoy]

Is yours Pharma or food grade?