Lanthanum to lower phosphate in rocks outside of aquarium

[kenchilada]

Removed the rest of rock yesterday.

Treating rock outside the tank seems very easy. I squirted 60mL into the stock tank directly and the water clouded up. I then started a drip of 60mL LaCl in 1L RODI overnight.

Next day….

 

[Randy Holmes-Farley]

About lanthanum chloride use.

IMO, the primary unknown is the reason some see fish toxicity and most do not.

Are there other things about it that you believe reflect uncertainty?

The fundamental chemistry processes are quite straightforward.

 

[kenchilada]

Now the 250G tank is left reading 10ppm phosphate. There is no more aragonite sink left in the tank, so I should be able to easily remove it. May try a 200G water change?

 

[kenchilada]

IMO, the primary unknown is the reason some see fish toxicity and most do not.

Totally agree. I was considering putting my sailfin tang in quarantine with clean saltwater and adding the lanthanum product as a test but chickened out.

My hunch is it’s not the precipitate, but that’s based on my own worthless anecdotes.

Are there other things about it that you believe reflect uncertainty?

The fundamental chemistry processes are quite straightforward.

I've only used Brightwell Phosphat-E, but here are some things...

Dosing into a sock seems of questionable value. It certainly does nothing for my fish. I suppose if you keep some portion of the precipitate out of the tank there is value in that (less test interference?), but people portray it as a solution to fish deaths. Many that use a sock and do not lose a fish report success and then post it as advice when most simply had no susceptible fish.

Further there is much uncertainty around micron size of mechanical filtration. An old post from Reef Central mentions "scientific experiments show 0.45 micron filters work the best", yet it is common to see everything from 1-25 micron socks recommended (usually attempting to benefit the fish).

I also think the conventional way we dose this into socks causes most LaCl product to simply flow out of the sock unreacted. I have seen posts state that most LaCl will react within 90 seconds.

I have seen no benefit from dillution and slow dripping into 1 micron socks versus adding product directly to the aquarium. The Brightwell instructions just say "Add product to aquarium near a mechanical filter or protein skimmer intake". It seems just as irritable to my fish and just as effective at removing PO4 regardless.

Poor test resolution at high range adds confusion around what is happening. Trying to interpret from 0-17PPM using six possible colors is not ideal. Plus lanthanum phosphate in the sample further confuses things.

It is commonly posted that LaCl is only effective to reduce phosphate to around 0.1-0.2ppm, which I can confirm in my usage as well. I have not found an explanation for why this happens but I would love to know why!

I have more thoughts but this is already long enough. For anyone reading, the above is anecdotes from my own usage and should not be construed as useful advice. I'm curious to understand it more, but it is a miracle product for my scenario and thankful to have it.

 

[Garf]

I have not found an explanation for why this happens but I would love to know why!

I've read somewhere that when the phosphate level is lower, the lanthanum turns into lanthanum carbonate instead of lanthanum phosphate. So instead of reducing phosphate its more likely to reduce alkalinity.
Whether or not phosphate is still likely to bind to lanthanum carbonate, I don't know.

 

[Randy Holmes-Farley]

I've read somewhere that when the phosphate level is lower, the lanthanum turns into lanthanum carbonate instead of lanthanum phosphate. So instead of reducing phosphate its more likely to reduce alkalinity.
Whether or not phosphate is still likely to bind to lanthanum carbonate, I don't know.

That is likely, IMO.

 

[kenchilada]

Problem solved. I am dosing beyond manufacturers recommended strength and see zero effects on my sailfin tang.

100mL Brightwell Phosphat-E undiluted over 24 hours on my 250G system.

Thanks @Garf for your input