Polymer based liquid phosphate remover...

[ReneReef]

Hi Randy, I recently came across the following product:

https://www.arka-biotech.de/en/products/phos-out-4
I would like to know what your take on it is?
Any idea what the active ingrediënt could be? Are their claims plausible or not?

The product is supposedly a polymer based liquid phosphate binder.
So, a product similar to lanthanum chloride, but without it's associated risks. That does sound great.

However, once again it is a product surrounded by mystery. There is no information on what it is, other than "a polymer". And of course they claim the product was especially developed by them... Seems very unlikely...
The SDS only gives some general information: watery solution, not flammable, violet-blueish in color, odourless, pH 3.5-5.5, solubility 99%.
Some of the information in the SDS is contradictory: it is supposedly non-toxic and not dangerous to ground or surface water. Yet, the product should not be disposed of in sewage or any other way that may lead to surface or groundwater exposure...
https://www.arka-biotech.de/fileadmin/Dokumente/Sicherheitsdatenblätter/SDS-PR.pdf
The only phosphate binding polymer I can find is Sevelamer, used in medicine to bind phosphate in the gut and prevent phosphate uptake.
However, Sevelamer is not water soluble. Then again, the product is 99% soluble, that leaves 1% room for insoluble stuff...

Thanks for your help!

 

[Randy Holmes-Farley Verified Community Expert]

lol

I invented sevelamer. It would be perfect, if it could work in seawater, but there’s too much competition by chloride and sulfate. No ordinary polymer will be better or work well.

The phos out says it is a GFO formulation

https://www.arka-biotech.de/en/products/phos-out-4-granules

• Iron-Hydroxide based formulation

 

[ReneReef]

Oh wow, what a coincidence! Very cool!

The product you link is their GFO, they have two different products with the same name the GFO and a liquid phosphate remover.

The website says about the liquid:
“Phos-Out 4 is a specially developed polymer-based phosphate remover for ideal use in any marine or freshwater aquarium.”

Then the question remains, could it be possible that ARKA has developed such a revolutionary polymer?

I’m skeptical. But, if they didn’t, then what are they selling?

I’m tempted to buy a bottle and ask a colleague at work if he can run a sample through the IR spectroscope.

 

[Randy Holmes-Farley Verified Community Expert]

I do not believe any purely organic polymer can bind appreciable phosphate from seawater. We made and tested many hundreds of possible phosphate binding polymers, and none are appreciably better than sevelamer, which itself won’t work in seawater.

Any cationic polymer will bind some phosphate from fresh water by ion exchange. Like the Chemipure claims, they may have evidence it works in fresh water, and either don’t know or don’t care that it won’t do so in seawater.

Most cationic polymers will bind some organic phosphate molecules. That is likely the only effect in seawater, IMO.

 

[MBruun]

I have used the liquid Phos-Out-4 for a few months now, replacing Lanthanum cloride, and it does bind phosphate. Adding it to saltwater with phosphate it generate white "powder like" cloud in the water, and no reaction when I dissolve it in rodi water.
I'm dosing it in my Clariesea fleece roller, which catch at least some of the particles, and then the skimmer, placed right after, remove some too. I can see that the skimmate has changed since I started using Phos-out-4. It generates larger particles as LC as the roller filter roles more than dosing LC in the same filter.

I have not noticed any reaction from fish, snails or corals (700 liter sps heave reef with 30+ fish). It would be nice if somebody could chip in with some experience or knowledge about this product.

Agree it might be stupid to add a product not knowing what it actually is, but have not found any bad stories about loses or bad outcome as results after using the product in reef tanks.
Changing from LC as I might have lost a few fish on that account but I can see the Mexican Turbo snails reacting on LC (falling of the rockwork).

 

[whitecloud]

lol

I invented sevelamer. It would be perfect, if it could work in seawater, but there’s too much competition by chloride and sulfate. No ordinary polymer will be better or work well.

The phos out says it is a GFO formulation

https://www.arka-biotech.de/en/products/phos-out-4-granules

• Iron-Hydroxide based formulation

Wow! Small world indeed! The drug we have used as a phosphate binder for millions of people with kidney disease/dialysis! Would make sense that someone might try that in an aquarium.

Thanks for letting us know we can put this product in the ‘snake oil’ category!

 

[Randy Holmes-Farley Verified Community Expert]

I have used the liquid Phos-Out-4 for a few months now, replacing Lanthanum cloride, and it does bind phosphate. Adding it to saltwater with phosphate it generate white "powder like" cloud in the water, and no reaction when I dissolve it in rodi water.
I'm dosing it in my Clariesea fleece roller, which catch at least some of the particles, and then the skimmer, placed right after, remove some too. I can see that the skimmate has changed since I started using Phos-out-4. It generates larger particles as LC as the roller filter roles more than dosing LC in the same filter.

I have not noticed any reaction from fish, snails or corals (700 liter sps heave reef with 30+ fish). It would be nice if somebody could chip in with some experience or knowledge about this product.

Agree it might be stupid to add a product not knowing what it actually is, but have not found any bad stories about loses or bad outcome as results after using the product in reef tanks.
Changing from LC as I might have lost a few fish on that account but I can see the Mexican Turbo snails reacting on LC (falling of the rockwork).

I wonder if it is just a flocculating polymer. :)

 

[MBruun]

Me too, but the Hannah checker Phosphorus ULR 736 show changes accordingly as I increase or decrease the dosing amount, so somehow it is binding PO4

 

[Randy Holmes-Farley Verified Community Expert]

Me too, but the Hannah checker Phosphorus ULR 736 show changes accordingly as I increase or decrease the dosing amount, so somehow it is binding PO4

Do you know it isn’t removing organics before they break down to phosphate?

A soluble polymer binding inorganic phosphate would not be expected to precipitate from seawater just because it bound phosphate.

I also contend the very high chloride and sulfate will out compete phosphate on any polymer.

 

[MBruun]

Do you know it isn’t removing organics before they break down to phosphate?

Don't know . Like when I was dosing LC I changed the dosing amount (diluted in ro water and dosed hourly) and measure again around a week after, so Phos-Out could be removing organics and thereby lowering PO4

 

[ReneReef]

I have used the liquid Phos-Out-4 for a few months now, replacing Lanthanum cloride, and it does bind phosphate. Adding it to saltwater with phosphate it generate white "powder like" cloud in the water, and no reaction when I dissolve it in rodi water.
I'm dosing it in my Clariesea fleece roller, which catch at least some of the particles, and then the skimmer, placed right after, remove some too. I can see that the skimmate has changed since I started using Phos-out-4. It generates larger particles as LC as the roller filter roles more than dosing LC in the same filter.

I have not noticed any reaction from fish, snails or corals (700 liter sps heave reef with 30+ fish). It would be nice if somebody could chip in with some experience or knowledge about this product.

Agree it might be stupid to add a product not knowing what it actually is, but have not found any bad stories about loses or bad outcome as results after using the product in reef tanks.
Changing from LC as I might have lost a few fish on that account but I can see the Mexican Turbo snails reacting on LC (falling of the rockwork).

Thanks for sharing your experience!

Could you try if the “cloud” appears in freshly prepared saltwater?

Me too, but the Hannah checker Phosphorus ULR 736 show changes accordingly as I increase or decrease the dosing amount, so somehow it is binding PO4

Don't know . Like when I was dosing LC I changed the dosing amount (diluted in ro water and dosed hourly) and measure again around a week after, so Phos-Out could be removing organics and thereby lowering PO4

Now I’m getting intrigued again.

 

[MBruun]

I just tested PO4 48 hours after increased dose of liquid Phos-out-4.
Usually I'm all good with PO4 below 0.2 and don't measure that often, but for input this thread and due to my light for 12 have only functioned with a third part of light meaning a lot less uptake from the corals

History:
36ml Phos-out / day dosed hourly (1.5ml per hour). dilution: 100ml in 300ml ro water.
PO4 < 0.2 (last reading = 0.190)
Light fixture failure, only 1/3 with light for 12 days (the middle of 3 sections)
05.06.2025 - PO4 = 0.233
05.06.2025 48ml Phos-out / day dosed hourly (2ml per hour)
07.06.2025 - PO4 = 0.208