Ferrous Sulphate FeSO4

[nakazoru]

Hi all;

In the quest battling PO4, GFO I have been using for 1 yrs, but I still experience Dinoflagate up til now. I comes down to restricting feeding, quit dosing phyto totally.

This week I bought FeSO4 from a lab distributor to try since it is reported that it reduces PO4 in fresh water. Later I found out that dosing kalkwasser will release the PO4 back to the aquarium. I abolish using it in my main tank since I drip kalkwasser. But I use it in my QT tank that I use to propagate mushie and zoo, and seems like the FeSO4 treatment.

I too stumble upon a article below that researcher did an open sea dump of FeSO4 to increase plankton activities with positive results. See here Open Sea Reseach

My primary intent is to reduce PO4 at a cost effective ways.

The cost issue with GFO is enormous compare to FeSO4 only 1/2 a teaspoon to reduce PO4 substantially. 1kg cost abt 10USD. So it last a long time.

While I'm not a Chemical guy by profession, what can I actually do to ultilise the use of FeSO4 without releasing PO4 back to the system when I dose kalkwasser?

 

[Habib]

I don't think you should compare freshwater with marine water when using ferrous sulfate.

The PO4 removal will be by binding of it to ferric oxide (from the ferrous sulfate) and removal by skimming.

I doubt that kalkwasser will make it more difficult since the pH range in the aquarium should be within normal ranges.

 

[bertoni]

An iron supplement can be useful for stimulating macroalgae growth, which is the topic of that article. Such growth will reduce phosphate. A commercial supplement like Kent's will supply chelated iron, which is likely a more effective approach than ferrous sulfate in salt water. I often dose chelated iron. The tank must have a refugium or macroalgae area for this to be useful. You also will have to harvest the algae by hand to remove the nutrients from the system.

This article discusses iron:

http://www.advancedaquarist.com/issues/aug2002/chem.htm

I agree that kalkwasser is unlikely to contribute to phosphate problems.

 

[nakazoru]

It guess you guys misunderstood me. The FeSO4 is indeed used as absorbent/reagent rather than a fertilizer to enhance algae growth. I really does not want to associate FeSO4 Fe additive but as a PO4 removal media.

Is it not the same as GFO that if used incorrectly that GFO will in time release PO4 back to the system.

I miss another link that uses FeSO4 for sole purpose of purification in marine aquarium. Please seehere

Hope you guys can help.

 

[bertoni]

That article is a bit ambiguous, but, in the end, the author recommends using limewater to remove phosphate. I don't know how valid his experiment with ferrous sulphate is, but I wouldn't add any to my tank just yet. Dr Holmes-Farley will be back tomorrow or so, and he might be able to help you.

 

[nakazoru]

Thanks you Jonathan.

You like me is a software guy. Screwing with chemical stuff. I use to automate a couple of industrial waste water treatent plant so juz trying those experience in marine.

In waste water treatment, the FeSO4 is added and let to settle and aggitate at the sedimentation pond. Impurities are oxidize as slugs at the bottom. The water is subsequently pump thru mechanical filtration to the next stage.

While I do not know the effect of the CaOH's (Kalkwasser) ion with slug form by FeSO4. Thus releasing PO4 back to the system. But I too find it abiguous in the statement "Limewater precipitates PO4 out of solution." i really thought that this statement should further reduce the PO4 not releasing it.

Really hope Dr Holmes-Farley can solve my question..

 

[nakazoru]

Wonder if the Dr. is back to help answer my question.

 

[bertoni]

I think he's still catching up.

 

[Randy Holmes-Farley]

Wonder if the Dr. is back to help answer my question.

Yes, but only if they are bumped up.
There are too many to read them all.

Later I found out that dosing kalkwasser will release the PO4 back to the aquarium.

I don't know if that is true or not. I address it here and in next months reefkeeping article, which is on phosphate:

http://www.reefkeeping.com/issues/2005-01/rhf/index.php#15

In general, I would not add soluble iron (like iron sulfate) in order to precipitate phosphate. That does not really export it, but just leaves it somewhere in the system as iron phosphate, which may be available to certain organisms. That is why the GFO particulates are preferable.

 

[nakazoru]

Well say a busy man. Dr. Can imagine so many posts that need yr addressing.

PO4 in the system when dosed with lime precipitate PO4 (optimal at PH 8.4) which is why lime retard algae growth. That essentially still leaves PO4 in the system. Combine with GFO, PO4 reduces substantially. Still dosing lime leaves PO4 in the system when used alone but not exporting it. Good part is that preciptation is not visible.

In the case of FeSO4, the binding occurs optimal at PH 8.8 leaving FePO4 in form of brown slug. If left in the system, it is very unsightly. FePO4 being heavy metals settles on the bottom making it quite difficult to remove in a close system. I have tested it in my QT tank.

My question being if the density of PO4 in water reduced substantially when uses FeSO4, will the PO4 crystal in LR and sand be release back to the water over days? And to what extend?

 

[Randy Holmes-Farley]

That essentially still leaves PO4 in the system.

Maybe. As I mention in the article above, the precipitate may be skimmed out, or buried deeply into solid calcium carbonate.

In the case of FeSO4, the binding occurs optimal at PH 8.8 leaving FePO4 in form of brown slug.

I don't believe that applies to seawater. The brown sludge that forms in seawater is iron oxide/hydroxide that is formed, not iron phosphate.

If you remove phosphate by any means, then some phosphate that is attached to the surface of live rock and sand can come back into the water. I'd plan on all of it being available unless it becomes buried under more CaCO3.

 

[GTR]

When using any of these products that precipitate phosphate is there any advantage to using it prior to a filter sock? If so what size range are we looking at? and I assume the binding reaction is pretty quick.

SteveU

 

[Habib]

<a href=showthread.php?s=&postid=7932042#post7932042 target=_blank>Originally posted</a> by Habib
................ .........

The PO4 removal will be by binding of it to ferric oxide (from the ferrous sulfate) and removal by skimming.

............................

 

[Randy Holmes-Farley]

Yes, I agree that there could be some of that, and some not removed. Do you have any measure of how much ends up being skimmed, typically, and how much settles out?

When using any of these products that precipitate phosphate is there any advantage to using it prior to a filter sock? If so what size range are we looking at? and I assume the binding reaction is pretty quick.

Such a sock might get clogged with CaCO3 if it is in the near vicinity to limewater addition, and the particles may well be too small to collect.

 

[nakazoru]

Thank you Dr. Randy Holmes-Farley, Habib and Jonathan for taking time to answer my question. I feel live a curious chemistry student again but at a much older age.

Now I will not be using FeSO4 in my closed system. As it really does not get exported well, maybe benefit the macroalgae. Skimming will remove the sludge but the sludge not 100% water borne to reach the skimmer. To make matter worst, I did not have a very efficient skimmer to work with.

I believe those commercial liquid phosphate binder works the same as here as mention by Habib to be skimmed out of the system. Measurement of phosphate at the skimmate rather than the system to see the phosphate exported.

I might work on a biweeky schedule to try out an open system to export PO4. Its something like this:
1. Water change 20% of Saltwater.
2. Treat the old 20% saltwater with appropriate dose of FeSO4 in a pail
3. Agitate Solution with mixture of air using a venturi pump to aid oxidation for 4 hrs.
4. Let the solution settle for 4 hours.
5. Feed water thru a filter block to extract purified saltater.
6. Saltwater return to tank.
7. Repeat step 1 until PO4 becomes accetpable range.

I'm going to test the PH and PO4 before and after these treatment. While mention in many article other ions may not be affected by FeSO4, I still contemplating if I need to test water parameters like Fe, salinity, KH/ALK etc? Some suggestion may be good.

My goal is to find a cheaper alternative, myabe even more labour intensive, to see if it is worth the effort at all.

 

[Randy Holmes-Farley]

The water removal/treatment/return is an interesting idea. Time consuming, but inexpensive. If you try it, let us know how it works out.

 

[nakazoru]

<a href=showthread.php?s=&postid=7949535#post7949535 target=_blank>Originally posted</a> by Randy Holmes-Farley
The water removal/treatment/return is an interesting idea. Time consuming, but inexpensive. If you try it, let us know how it works out.

Will do that, and post the results. Thanks again.

 

[GTR]

5. Feed water thru a filter block to extract purified saltater.

Micron range for this filter should be?

SteveU

 

[Randy Holmes-Farley]

I'd personally just let it completely settle out and not filter it. I suspect fine filters would clog if they were really taking out much.

 

[nakazoru]

Hi all;

Being weekend today, I did a out-of-system PO4/Silica removal Test using a home pail.

I did a PO4 measurement and it reads 0.3-0.5mg/l using Topic Marine Test Kit.

The pail is 7G of SW of my 40G system. It is now agitated by a venturi pump. And in the 1st hour of the Agitation process.

This picture show the treatment in process..