Lanthanum Chloride Use in a Large Reef

[reefdude3749]

Bertoni and TMZ....thanks for the responses.

I have not noticed my alkalinity dropping at all, just thought I should say that. If the lanthanum reaction to the carbonate is becoming dominate due to the rate inhibiting effect of the very low phosphate...shouldn't I see the carbonate start to drop? Maybe the impact is within the error of our hobby test instruments?

Also, is the reaction to either the phosphate or the carbonate essentially instantaneous? I ask this as I would not want unreacted lanthanum to enter the DT. Coincidently, I have never seen any cloud in my tank during my LC drips, but I am also running all of my treated water through 1u socks.

Thanks in advance, JPB

 

[bertoni]

I think it'd take a lot of lanthanum to make much of a difference in the measured alkalinity. Remember that phosphate is usually at 1 ppm or less, and carbonate and bicarbonate are at more like 100 ppm:

http://reefkeeping.com/issues/2005-11/rhf/index.php#6

I don't know how quickly the reaction might be. I've never needed to use lanthanum chloride. It seems to be relatively quick.

 

[reefdude3749]

Thanks.

I reviewed the Wastewater treatment article from the EPA circa 1970, and the chemistry has not changed... Anyway, they state that the reaction rate is very fast..."complete is less than 1 second and are probably nearly instantaneous" at 0.5:1 lanthanum to orthophosphate molar ratios...I am interested in the competing kinetics of the lanthanum carbonate reaction...I assume it is also very fast...so as long as you catch all of the precipitates one should be able to get the phosphate to an even lower level (if desired) with likely some secondary impact such as lowering alkalinity. Make sense?

Thanks again, JPB

 

[tmz]

I'm not sure about the exact kinetics for lanthanum carbonate. My recollection is lanthanum binds with PO4 preferentially vs carbonate.

The more pre filter water volume to which you expose lanthanum the larger the pool of carbonate and PO4 to which it can bind will be. Lanthanum itself is smaller than water ;so it will pass through a filter that water can pass.

 

[Dimorb]

Help!

Help!

Hello everybody.

I'm having some trouble hope you can help.

I dose lanthanum chloride into my pipe work that goes down to a clarisea sk5000 roller filter after the filter the water goes into the sump - skimmer - filters etc..

I dilute my seaklear commercial 7 ml lanthanum chloride / 1 L of water. Dose it over 24 hours distributed on 150 occasions a' 3,6 ml/dose.

I get the wanted effect in lowering phospates but it also shows on ICP testing and the amount in the water is rising. 4 ug/l last time and 11 ug/l this time.

What do you recommend? Maybe the clarisea sk5000 isnt suitable for this?

I've also noticed an increase in other of other substances like aluminium, lithium and barium do you know if the lanthanum could "free" other substances?

 

[bertoni]

The filter might not be removing the precipitate, but that won't affect the phosphate reduction over the short term. It'd take a low pH event to free the phosphate in the precipitate, if my memory is correct.

 

[Dimorb]

The filter might not be removing the precipitate, but that won't affect the phosphate reduction over the short term. It'd take a low pH event to free the phosphate in the precipitate, if my memory is correct.

Thank you for your responce. I'm concerned since the ICP shows "free" lanthanum chloride.

Shouldnt it be impossible to have free lanthanum when I also have phospates and high carbonates.. it should react shouldn't it?

Lanthanum that reacted with phospates and/or carbonates get stuck in the fleece so the free lanthanum must be going through the filter without reacting with neither phosphate or carbonate. Does that mean I need to increase or decrease the flow when dosing? Should I increase och dilute the solution?

Do you have any other advice except waiting for ICP to see if the lanthanum is contaminated?

Is there something that can be done to trap lanthanum that is "free" in the water?

 

[bertoni]

Lanthanum phosphate will dissolve to a small degree in saltwater, so the presence of small amounts of lanthanum in solution is to be expected.

If the lanthanum passes through the fleece, it'll react later up to the solubility limits. If your tank isn't getting any precipitate, the flow rate likely is fine as is.