Lanthanum Chloride and GFO Effects

[rockskimmerflow]

I've been curious for a long time if there is any concrete data regarding the depletion of alkalinity as a result of the use of lanthanum chloride or GFO. More specifically, do the relative concentrations of phosphate and carbonate play a role in how much the carbonate concentration is affected. If so are there any equations that can be applied to determine the amount of carbonate depletion per unit of phosphate binder added to seawater. I suspect that it's more complex than that, but I can dream.

Would it be fair to say the the propensity of Lanthanum to deplete alkalinity would increase when added to a system with very low phosphate concentrations? And conversely, would one observe a less pronounced effect per unit of lanthanum in a high phosphate scenario.

In any case, I've found both lanthanum and gfo to be excellent methods of phosphate control but prefer to use GFO unless substantial and immediate phosphate reduction is needed. The potency of lanthanum and its potentially unknown side effects deter me from using it on a daily basis. Was hoping some light could be shed on process by which lanthanum chloride and gfo can impact an aquariums alkalinity.

I consider alkalinity as a parameter of pinnacle importance with regard to sps coral health and color so I'd like to minimize any chance of instablility or longterm drift caused by the regular use of phosphate reduction methods. Hoping to gain a better understanding of this phenomenon from the godfather of phosphate management himself. Thanks in advance Randy!

 

[mikellini]

Following... interesting topic

 

[Randy Holmes-Farley]

I do not have data, but it is clear that GFO does not deplete alkalinity appreciably except as it might spur the precipitation of calcium carbonate. There may be a small effect depending on the surface state of the GFO, but that will be instantaneous and minor.

Lanthanum, however, will unquestionably deplete alkalinity as it nearly all ends up as lanthanum carbonate or lanthanum phosphate, both if which deplete alkalinity. So if you knew how much lanthanum you actually dosed, you can determine how much alk must decline.

Yes, the less phosphate and the higher the alkalinity, the greater the percentage of lanthanum carbonate. pH may also play a role, although predicting that is more complex.

 

[rockskimmerflow]

Thanks for the info Randy. I'm glad to hear the use of GFO is unlikely to cause any drastic changes in alkalinity.

It sounds like I'll have to take a few samples of saltwater of known alkalinity and phosphate concentrations and react them with a given quantity of lanthanum to measure the effect at different parameters.

I'd be interested to see what the result would be if I added exactly enough lanthanum chloride to a sample to react with all of the measure phosphate to achieve 0.00 exactly. Would eventually all of it end up being bound with phosphate or would a fraction of the lanthanum remain bound only to carbonate with some phosphate remaining?

I'm quite rusty on my chemistry so I'm grappling with how lanthanum phosphate and lanthanum carbonate both deplete alkalinity. Lanthanum carbonate I understand, but lanthanum phosphate not so much. I always imagine lanthanum in it's 3+ state binding to phosphate on a one to one basis and the unreacted lanthanum binding to carbonate 2 La to 3 carbonate ion ratio. I'm very curious to know how lanthanum phosphate removes alkalinity. I would guess that it has something to do with Lanthanum's tendency to bind to hydroxide, or that it prefers to form complexes with multiple lanthanum ions and both phosphate and carbonate ions involved. Those guesses are probably way off. I've been puzzled by this topic since I started playing around with lanthanum chloride.

 

[Randy Holmes-Farley]

There will definitely be lanthanum carbonate formed no matter what the phosphate concentration, but if phosphate is real high and you don't bring it to zero (say, 1 ppm to 0.5 ppm), you'll bind relatively more phosphate. I expect you always bind more carbonate than phosphate by a considerable margin, based on the doses people use.

BUT, you cannot detect the difference by alkalinity alone because phosphate contributes to alkalinity too. Phosphate is part of total alkalinity.

Here's the equation for it:

Chemistry and the Aquarium: What is Alkalinity? ? Advanced Aquarist | Aquarist Magazine and Blog

from it:

TA = [HCO₃^-] + 2[CO₃^--] + [B(OH)4^-] + [OH^-] + [Si(OH)₃O^-] + [MgOH⁺] + [HPO₄^--] + 2[PO₄^---] - [H⁺]

 

[rockskimmerflow]

Ahh I had forgotten that phosphate was included in total alkalinity. That answers my question about lanthanum phosphate. Fortunately, from the article it looks like it makes up so small a fraction of the total alkalinity that the effect could be largely ignored when calculating overall alkalinity loss due to lanthanum input.

Glad to hear that in seawater carbonate is the primary species with which lanthanum prefers to affiliate. It makes things a lot simpler knowing that regardless of phosphate concentration a lot of carbonate will be reacted with by a lanthanum chloride dosage.

I knew that borate, carbonate, and bicarbonate formed the primary basis for total alkalinity but I had completely forgotten about silicate and the other minor players involved. Thanks again for all the help Randy. I feel much better armed to tackle the task of adjusting for alkalinity loss due to lanthanum.

 

[Randy Holmes-Farley]

You're welcome.

While I haven't calculated it, I think if you know the amount if lanthanum you are dosing (in grams or moles) we can calculate the expected alkalinity loss.

 

[Cory]

does lanthanum carbonate remove po4 from seawater?

 

[Randy Holmes-Farley]

Some on its surface, probably, just like calcium carbonate does.

 

[Cory]

Some on its surface, probably, just like calcium carbonate does.

So could i add sodium bicarbonate to a cup of water and lanthanum chloride to make it lanthanum carbonate?

 

[Randy Holmes-Farley]

So could i add sodium bicarbonate to a cup of water and lanthanum chloride to make it lanthanum carbonate?

Yes. Or you can buy it. Why do you want to make it?

 

[Cory]

Yes. Or you can buy it. Why do you want to make it?

Its cheaper than buying pills to reduce po4. Im thinking of putting the lanthanum carbonate powder into a filter sock to try and see the impact on po4. This way no alk is depleted.

 

[Randy Holmes-Farley]

Its cheaper than buying pills to reduce po4. Im thinking of putting the lanthanum carbonate powder into a filter sock to try and see the impact on po4. This way no alk is depleted.

Ok, let us know if you see a significant reduction.

 

[Halal Hotdog]

Any updates on efficacy of adding lanthanum carbonate to bind phosohate?

 

[Big E]

Either could be simply a result of lower PO4 increasing coral growth. You should be able to confirm by seeing a drop in calcium levels as well.

 

[1979fishgeek]

I know this is a old thread, but I dosed lanthanum chloride for the first time yesterday and just had a drop in alkalinity. I dosed 30 drops yesterday and today (60 drops in totally to a 1200l system) into my Skimmer and Alk has dropped from 7.8 to 6.6! What’s more frustrating is when I tested Phosphate with Hanna ULR it’s reading slightly elivated phosphate.

Now I’m having to play about with Kalk in my ato and adjust calcium reactor, think it’s time for a water change and I’m going back to NoPox and a Cheato refugium!

I def need to follow the advice “if it ain’t broke don’t fix it” Lol

 

[User1]

I know this is a old thread, but I dosed lanthanum chloride for the first time yesterday and just had a drop in alkalinity. I dosed 30 drops yesterday and today (60 drops in totally to a 1200l system) into my Skimmer and Alk has dropped from 7.8 to 6.6! What’s more frustrating is when I tested Phosphate with Hanna ULR it’s reading slightly elivated phosphate.

Now I’m having to play about with Kalk in my ato and adjust calcium reactor, think it’s time for a water change and I’m going back to NoPox and a Cheato refugium!

I def need to follow the advice “if it ain’t broke don’t fix it” Lol

Someone here has a really decent thread or video on how they dose Lanthanum Chloride using filter socks. Maybe it was Slief, not sure. I've personally never used it on a running system but I did use it while cleaning up new Pukani rock I used earlier in the year. That is how I found his thread which provided a lot of good information on what I should expect to see.

Sorry that I have no solution or ideas other than if it is something you want to do see if his video can shed any light at least how he does it.

 

[Frogger]

I know this is a old thread, but I dosed lanthanum chloride for the first time yesterday and just had a drop in alkalinity. I dosed 30 drops yesterday and today (60 drops in totally to a 1200l system) into my Skimmer and Alk has dropped from 7.8 to 6.6! What’s more frustrating is when I tested Phosphate with Hanna ULR it’s reading slightly elivated phosphate.

Now I’m having to play about with Kalk in my ato and adjust calcium reactor, think it’s time for a water change and I’m going back to NoPox and a Cheato refugium!

I def need to follow the advice “if it ain’t broke don’t fix it” Lol

What are your nitrates at? Years ago my phosphates were artificially high because my nitrates were at zero. Everything I did (lanthanum chloride, GFO)my phosphates would not drop, until I raised my nitrates and my phosphates dropped without having to do anything other than raise my nitrates.

 

[1979fishgeek]

What are your nitrates at? Years ago my phosphates were artificially high because my nitrates were at zero. Everything I did (lanthanum chloride, GFO)my phosphates would not drop, until I raised my nitrates and my phosphates dropped without having to do anything other than raise my nitrates.

My nitrates are high at the moment, I switched from NoPox dosing to vodka/vinegar and did not take into account that I need to dose more for same result. My Nitrates have gone from almost undetectable to 20ppm.

I’ve stoppe the lanthanum now, I’m doing water changes and switching back to the NoPox, if I need to reduce phosphate I’ll just use GFO. I run my alkalinity at around 7-8dkh so even a slight drop takes it too low unfortunately.