Using Ferrous Chloride to remove phosphate, possible?

[ivans75]

Hi

Due to the cost of commercial aquarium use phosphate remover such as rowaphos, I am currently seeking alternatives in replacing the media.

I am looking for gfo products but I couldn't find one in my country, but there is powdered version of iron oxide available. And this product is intended to use for color pigmentation.

And I came across this website http://www.lenntech.com/phosphorous-removal.htm

And there, it says that ferrous chloride and ferrous sulphate can also remove phosphate. And I am actually quite happy to hear this as ferrous chloride in granule and crystal form is available in chem store.

These are the products available, maybe some of you chemical experts can tell me what are they and if they are good enough to replace rowaphos
2064-05 Ferrous Chloride, 4-Hydrate, Crystal, BAR 2.5 kg
2064-01 Ferrous Chloride, 4-Hydrate, Crystal, BAR 500 g
2070-05 Ferrous Sulfate, 7-Hydrate, Granular, BAR, ACS Reagent 2.5 kg
2070-01 Ferrous Sulfate, 7-Hydrate, Granular, BAR, ACS Reagent 500 g

But I am actually concerned now that the website is actually a water treatment company website who actually deals with fresh water treatment...wonder if the use of ferrous chloride or sulfate will not have negative effect in salt water aquarium. I do have a feeling it won't make any different as our freshwater also contains almost the same minerals as sea water has although it's in different composition percentage.

I am trying to look around tomorrow at some water treatment stores and see if they can hook me up with any media provider such as adsorpas, I couldnt find the seller here in Indonesia.

Thanks in advance...your thought please...

[HighlandReefer]

It is my understanding that you can use Ferrous Chloride in seawater for removing phosphate. ;)


See this thread for more details with remarks from Habib, Boomer and Randy:


phosphate removal through FeCl
http://www.reefcentral.com/forums/showthread.php?t=857050&highlight=ferrous+chloride

[HighlandReefer]

The ferrous chloride will deplete alkalinity. ;)

A quote from Randy in the above thread:

"How much of a effect would the HCl give ?

Depends on how much you add.

Seriously, I do not know how much one might add this way, but if you add as much as one adds GFO, it could be large.

25 grams of FeCl3 (0.15 moles) in a 100 gallon tank will deplete alkalinity by 0.45 moles/100 gallons = 1.2 meq/L.

That adds about the same amount of iron as 15 grams of GFO.



__________________
Randy Holmes-Farley
Club 65535

Current Tank Info: 120 mixed reef"

[disc1]

The article that the OP linked and the post that Highland Reefer just linked are both about ferric chloride FeCl3. Ferrous chloride is FeCl2. Ferric ions will bind with phosphate. Ferrous ion will first deplete oxygen then bind to phosphate.

That little difference in oxidation state is a pretty big deal.

[HighlandReefer]

Thanks fro the info David. Good to know. ;)

[disc1]

To give an idea of the oxygen sucking power of Fe(II) ions, solutions of FeCl2 are used in bacterial growth media to create anaerobic conditions without needing to keep the culture under anaerobic atmosphere.

[disc1]

However, even though ferric ions will bind phosphate, think about dosing iron to the tank before you do it. I know that people who dose iron do it at very low concentrations. It tends to favor algae growth IIRC. I know Randy doses iron for his macro, so look at the thread he posted in and see if he says anything about it.

For phosphate removal in the reef tank, I think you want an insoluble form of iron(III). Like Fe2O3.

[ivans75]

Wow slow down guys, I am bit slow bout this hehehe...

Ok so... In conclusion, ferrous chloride can be used, but it will deplete oxygen, reduce alkalinity and add soluble iron into the water, am I correct? If ferrous iron wil deplete oxygen, i don't think it matters much in my tank as I am using 2 skimmers running.

And increase iron in the water will lead to algae growth? Thought algae can only happen with nitrate, po4 and light...

I have 2 tanks at the moment. 1 has 1.0 ppm po4 and the other one got 0.1. The later one has np biopelet fluidized.

Would it be ok if I use a little of ferrous chloride in fluidzed reactor, let's say 250 gram and increase gradually when needed?

[disc1]

Ok, maybe I should be more clear about the real point.

Do not put ferrous with an -ous at the end means iron(II) in your tank.

If you want to use what was being used in the article int the OP, that is ferric with an -ic at the end means iron(III). There is a big difference between the two.

[ivans75]

ah ok. Thanks...so, ferric chloride should do. But both does remove po4 right? what's the big difference?

[ivans75]

there is no ferric chloride in the shop that I was reffering to..means I have to do some more hunting, but they go tthese:
2024-05 Ferric Oxide, Powder, BAR 2.5 kg
2024-01 Ferric Oxide, Powder, BAR 500 g
2046-05 Ferric Sulfate, n-Hydrate, BAR 2.5 kg
2046-01 Ferric Sulfate, n-Hydrate, BAR 500 g

The ferric oxide is my choice but it's powder...not granule

[ivans75]

there is no ferric chloride in the shop that I was reffering to..means I have to do some more hunting, but they go tthese:
2024-05 Ferric Oxide, Powder, BAR 2.5 kg
2024-01 Ferric Oxide, Powder, BAR 500 g
2046-05 Ferric Sulfate, n-Hydrate, BAR 2.5 kg
2046-01 Ferric Sulfate, n-Hydrate, BAR 500 g

The ferric oxide is my choice but it's powder...not granule

[ivans75]

ok there is one selling ferric chloride hexahydrate, is that the same thing?
And just curious, can you actually buy some 1m thick iron wire and cut them up in small piece like 3-4 ml long and put them in the gfo and let it rust in the water? It's the same thing right? RUst is ferric oxide...

[disc1]

ah ok. Thanks...so, ferric chloride should do. But both does remove po4 right? what's the big difference?

Iron in its 3+ oxidation state binds to phosphate.

Iron in its 2+ oxidation state doesn't. It just wants to be 3+ really bad. How it gets there is to stick an electron onto a molecule of oxygen making a hydroxide ion and a hydroxide free radical. That radical is a strong oxidizer. You have also taken oxygen out of the water. But at the end of the reaction, the iron(II) has become iron(III) which will bind phosphate.

But you don't want all that oxidation reaction to get there going on in your tank. So you should definitely use an iron(III) if you are adding it to the tank.

[disc1]

ok there is one selling ferric chloride hexahydrate, is that the same thing?
And just curious, can you actually buy some 1m thick iron wire and cut them up in small piece like 3-4 ml long and put them in the gfo and let it rust in the water? It's the same thing right? RUst is ferric oxide...

All the hexahydrate means is that there are 6 water molecules for every molecule of FeCl3 in the crystals. It doesn't change the chemistry, but it doesn change how you would weight it out. The hydrate has less iron per gram than the anhydrous because part of the weight is water.

[ivans75]

Iron in its 3+ oxidation state binds to phosphate.

Iron in its 2+ oxidation state doesn't. It just wants to be 3+ really bad. How it gets there is to stick an electron onto a molecule of oxygen making a hydroxide ion and a hydroxide free radical. That radical is a strong oxidizer. You have also taken oxygen out of the water. But at the end of the reaction, the iron(II) has become iron(III) which will bind phosphate.

But you don't want all that oxidation reaction to get there going on in your tank. So you should definitely use an iron(III) if you are adding it to the tank.

Thanks very much, good to ask first...ok ferric is the man...
So adding bits of irons in the reactor will also be the same story, it goes to Fe(2) first before it becomes Fe (3)?

[disc1]

In the link that HighlandReefer posted, Randy, Boomer, and Habib don't make it sound like a great idea. Chemically relevant, but not a great idea.


Here's the link again.

http://www.reefcentral.com/forums/showthread.php?t=857050&highlight=ferrous+chloride

[ivans75]

All the hexahydrate means is that there are 6 water molecules for every molecule of FeCl3 in the crystals. It doesn't change the chemistry, but it doesn change how you would weight it out. The hydrate has less iron per gram than the anhydrous because part of the weight is water.

So I would need more ferric chloride hexahydrate than just using a regular unhydrous ferric chloride? Like 6 times more? So what is the form of hexahydrate? powder?

[disc1]

So adding bits of irons in the reactor will also be the same story, it goes to Fe(2) first before it becomes Fe (3)?

Yes, it's going to pull oxygen. And at the end of the day, most of the iron will still be buried. GFO has a high porosity and a high surface area. So for the same amount of stuff, there is more iron exposed and the efficiency is much higher.

[disc1]

So I would need more ferric chloride hexahydrate than just using a regular unhydrous ferric chloride? Like 6 times more? So what is the form of hexahydrate? powder?

The hydrate is a powder. It has water trapped in the crystal lattice.

To figure the weight you need to know how to do math in moles.

Like this.

FeCl3 weighs 162.2 g/mol as anhydrous

FeCl3 * 6H2O (the hexahydrate) weighs 270.3 g/mol.


So you would need 1.66 times more of the hexahydrate to get the same amount of iron.

Now here's the big caveat. Biologists, environmental scientists, chemical engineers, pretty much everyone but the chemists forget to include the *6H2O when they write their recipes. You never know if they meant 2g of anhydrous FeCl3 or 2g of hexahydrate. They don't always say.

Usually they mean the most common form, which for FeCl3 is the hexahydrate. But you really never know.

[ivans75]

Thanks for the link, appreciate that. I don't understand why there are no granular form of ferric oxide here...can you tell me who or what industry might sell those? I've contacted a water treatment shop, they got no clue of what is it. If I could I would stick to the gfo.

And umm as I am living in the tropic, I have access to some red earth or laterite. And they make red/orange redish brick for building construction (houses) from this laterite clay. The way they make this brick is that they heat the clay 24 hours.

I am thinking of breaking a clay brick in very small pieces similar to GFO, would that do the job?

This laterite clay/brick contains iron oxide as the laterite also has iron oxide content makes it red color.

[ivans75]

The hydrate is a powder. It has water trapped in the crystal lattice.

To figure the weight you need to know how to do math in moles.

Like this.

FeCl3 weighs 162.2 g/mol as anhydrous

FeCl3 * 6H2O (the hexahydrate) weighs 270.3 g/mol.


So you would need 1.66 times more of the hexahydrate to get the same amount of iron.

Now here's the big caveat. Biologists, environmental scientists, chemical engineers, pretty much everyone but the chemists forget to include the *6H2O when they write their recipes. You never know if they meant 2g of anhydrous FeCl3 or 2g of hexahydrate. They don't always say.

Usually they mean the most common form, which for FeCl3 is the hexahydrate. But you really never know.

Riighht...in moles...hmmm back to high school...thinking thinking...naah cant remember lol...

Ok let's leave alone the dose for now...I need to get the right stuff first.

Hey thanks very much bud.

[disc1]

Thanks for the link, appreciate that. I don't understand why there are no granular form of ferric oxide here...can you tell me who or what industry might sell those? I've contacted a water treatment shop, they got no clue of what is it. If I could I would stick to the gfo.

And umm as I am living in the tropic, I have access to some red earth or laterite. And they make red/orange redish brick for building construction (houses) from this laterite clay. The way they make this brick is that they heat the clay 24 hours.

I am thinking of breaking a clay brick in very small pieces similar to GFO, would that do the job?

This laterite clay/brick contains iron oxide as the laterite also has iron oxide content makes it red color.



Depends on what else is in the clay.

[HighlandReefer]

Hi

Due to the cost of commercial aquarium use phosphate remover such as rowaphos, I am currently seeking alternatives in replacing the media....

Why not look into lanthanum chloride?

[bertoni]

I agree with looking into lanthanum chloride. I don't know whether it's easily available in your location, but it can be used successfully. GFO can be regenerated, as another cost-reducing approach.

[ivans75]

ah lanthanum chloride, i've never heard of it before but thanks for pointing it out. What is this thing exactly?

[HighlandReefer]

Lanthanum Chloride Thread:
http://www.reefcentral.com/forums/showthread.php?s=&threadid=1333212&highlight=lanthanum+chloride

Lanthanum Chloride - Aquality Symposium
1st International Symposium of Water Quality & Treatment in Zoos & Aquaria
http://www.aqualitysymposium.org/phpBB2/viewtopic.php?t=6&postdays=0&postorder=asc&start=0&sid=641009192b567cfd6a779ce4041f98b0

--------------------------------------------------------------------------------

Lanthanum chloride or lanthanum carboxylate for orthophosphate
removal in seawater aquarium - a feasibility study
YING ZHANG; KAR SONG WONG
http://aalso.org/2009presentations/ZhangWongOrthophosphateRemovalPaper.pdf

From it:

"Conclusion
Although all lanthanum compound tested can remove PO4
3- from seawater, the
efficiency of removal depends on the pore size of filters. Lanthanum compound could
pass through filters and increase turbidity inside pool. Barry and Meehan (2000) have
found lanthanum can cause significant mortality to Daphnia due to cloggin g filtration.
Small lanthanum particles passed into pool could also potentially be trapped by gill
lamellae of fish.
Therefore, application of lanthanum compound to an aquarium has to managed very
carefully and better to be conducted in a side loop equipped with high efficient filters to
avoid any potential adverse impact on aquatic organisms due to leakage of lanthanum
compound to the pool.