Lanthanum Chloride PO4 Binding Potential

[chipmunkofdoom2]

Hi everyone. I had a question about lanthanum chloride (specifically, Seaklear) and how much phosphate it can potentially remove. I have the 32oz bottle of Seaklear that claims to remove 9,000ppb of phosphates from 10,000 gallons. I did some math in an attempt to figure out how much PO4 one mL will remove, and it seems very high. I'd like some confirmation that my findings are correct.

The bottle claims to remove 9,000 ppb (9ppm or mg/L) of phosphates from 10,000 gallons (37,854 liters). If the bottle removes 9 mg/L from 37,854L, that's a total reduction of 340,686mg PO4 (9mg/L * 37,854L total). If that's the case, and the bottle is about 946ml, then each mL of Seaklear will remove 360 mg/L of PO4 (340,686mg total PO4 / 946ml = 360.133 per ml). If my math is correct, that means dosing 1mL of Seaklear to a 100 gallon (378 L) aquarium would remove 360mg total, which would equate a 0.952 ppm reduction in PO4 overall (360mg removed / 378L total = 0.952mg/L).

Is my math correct? I understand that lanthanum is not 100% efficient at PO4 removal since it can sometimes bind to carbonate and precipitate as lanthanum carbonate. But could one mL of this stuff really bind up to 360mg of PO4?

 

[Randy Holmes-Farley Verified Community Expert]

Is this a solid material? (then yes, it might do what they claim).


Lanthanum phosphate is LaPO4. Forming that compound would be the most possible it might remove (it may be a lot less).

LaPO4 is 60% by weight lanthanum and 40% by weight phosphate.

So 0.60 gram of lanthanum (1.06 grams of dry lanthanum chloride) will remove 0.4 grams of phosphate.

If you use a solution, the MSDS I saw said 35-65% lanthanum salt. So I cannot really saw exactly what the concentration is.

If you really wanted to remove 9 mg/L from 37,854 L, you want to remove 340,686 mg (341 grams) of phosphate.

That would require 904 grams of dry lanthanum chloride.

If we assume the 32 oz bottle of Seaclear really contains 32 ounces of weight, then it contains 32 oz of lanthanum chloride which is 901 grams. No weight left for water, but if it is a dry solid it could possibly do what is claimed.

 

[chipmunkofdoom2]

Is this a solid material? (then yes, it might do what they claim).

Thanks Randy. The Seaklear Phosphate Remover is a liquid. The package claims that the whole 32 fluid ounces will remove up to 9,000ppb (9ppm) from 10,000 gallons. With the numbers you provided it sounds like this stuff will remove nowhere near what they say it will.

What do you think would be a sensible way to approach the dosing of this solution? Perhaps assume the maximum concentration listed on the MSDS, just to be safe, then adjust up from there as needed?

If we assume the Seaklear has a concentration of 65% LaCl2, then at most the liquid would have a 650g/L concentration. This would mean there would be at most 650mg LaCl2 per mL of the solution. If 1.06g LaCl2 removes 0.4g of PO4, then it takes 2.65g of LaCl2 to remove 1g of PO4. So, if we were to dose 1mL of the solution, at most it would bind 245mg of PO4 (650mg / 2.65g LaCl2 to remove 1g PO4 = 245mg PO4 removed). Does that sound correct?

I don't want to necessarily calculate exactly how much PO4 I want to remove and dose the exact amount of Seaklear necessary to do so. I just don't want to dose too much, and I'd just like to get an idea of the relative concentration of the solution before I dose anything.

 

[drawman]

Following as I will be using this soon myself in a curing bin.

 

[Randy Holmes-Farley Verified Community Expert]

If the 32 ounces is a liquid volume measurement rather than the weight, the density might make it weigh enough to match what they claim.

 

[chipmunkofdoom2]

If the 32 ounces is a liquid volume measurement rather than the weight, the density might make it weigh enough to match what they claim.

Correct, the container is 32 ounces is a volume measurement. I suppose I can just use their stated removal (9ppm in 10,000 gallon) as a starting point to be conservative, and go from there.

Thanks Randy!

 

[drawman]

Correct, the container is 32 ounces is a volume measurement. I suppose I can just use their stated removal (9ppm in 10,000 gallon) as a starting point to be conservative, and go from there.

Thanks Randy!

Have you seen the long thread on the other forum? It's worth a read and may help to determine a rough starting point. I would just go slow, use less than you think, and keep an eye on alkalinity.

I'm assuming you'll use it in tank with a 5-10 micron sock?

 

[chipmunkofdoom2]

Have you seen the long thread on the other forum? It's worth a read and may help to determine a rough starting point. I would just go slow, use less than you think, and keep an eye on alkalinity.

I'm assuming you'll use it in tank with a 5-10 micron sock?

I believe I've seen that thread. I'm doing a bit of a different approach, which is why I needed to understand the relative concentration and ability of LaCl2 to remove PO4.

I have reason to believe my rock is still leaching phosphates. My plan is to remove my rocks one at a time from my display, place it in a bucket with saltwater, a powerhead and heater, then add much more LaCl2 than necessary in an attempt to quickly strip the PO4 from the rock. I'll allow the rock to circulate with the LaCl2 for a while, rinse the rock in clean saltwater, then return to my display. A week or so later, I'll repeat with a different rock. Because this process is being undertaken in a container with no livestock, I don't need to worry about the LaCl2 precipitating carbonate or filtering out the precipitants.

 

[drawman]

I believe I've seen that thread. I'm doing a bit of a different approach, which is why I needed to understand the relative concentration and ability of LaCl2 to remove PO4.

I have reason to believe my rock is still leaching phosphates. My plan is to remove my rocks one at a time from my display, place it in a bucket with saltwater, a powerhead and heater, then add much more LaCl2 than necessary in an attempt to quickly strip the PO4 from the rock. I'll allow the rock to circulate with the LaCl2 for a while, rinse the rock in clean saltwater, then return to my display. A week or so later, I'll repeat with a different rock. Because this process is being undertaken in a container with no livestock, I don't need to worry about the LaCl2 precipitating carbonate or filtering out the precipitants.

I am doing the same good luck . Much safer this way.