Iron consumption in SPS tank

[Tenshoa]

My apologies if this has been asked before.

Can someone help me with some accurate information as to iron consumption in an sps tank that utilizes chaeto? I have found that dosing iron (up to .15 ppm) has had a significant effect on my coral coloration. I have taken photos over a 3 week period without having changed anything else in my tank in order to keep my results as controlled as possible for a home setting. While continuously testing my iron levels, I noticed that the iron depletes rather quickly (in a 3-4 day time span). This seems to be an unrealistic amount to keep up with. For some reason, I am sensing that there may be a link between my chaeto and iron uptake. Can anyone confirm this?

All parameters in my tank are for the most part, rock solid and do not fluctuate hardly at all. My PH remains between 8.15-8.2, calcium is almost at a constant 490-500ppm, magnesium at 1490-1500, KH at 8.5, NO3 at 2ppm, and PO4 is undetectable. These parameters do not fluctuate outside of the aforementioned readings. I can test my water 2 weeks apart and the parameters are still holding stable. I dose Kalkwasser mixed with vinegar via a dosing pump 24/7 as to mitigate PH spikes. The tank is beautiful, clean, and the livestock couldn't be happier. I show growth and color to the point that local hobbyists think I have some sort of secret. I would like to continue to contribute to the enhanced coloration which I have to believe to be due, in part, to the iron supplementing, but I have to know where it is all going.

Any insight would be helpful, but please be ready to back it up with evidence.

 

[Randy Holmes-Farley]

IMO, that iron level is unnecessarily high, higher than needed by marine organisms. The surface iron concentration on a coral reef is more like 0.000006 ppm. At that level it is limiting to some organisms, and dosing it a bit higher is likely useful in an aquarium (I regularly dose iron), but I think that 400,000x the NSW level is likely overkill. There are potential drawbacks to elevated iron (potential for cyano and algae, for example), but all that said, if you like the effects, I wouldn't say you need to dose less. But as an experiment, you might try dosing 1/10 or 1/100 of what you are now and see if anything changes. IME, 10-100 times less than you are dosing (0.15 ppm) is more than enough for a week in many aquaria.

Iron will be both taken up and precipitated from the water as insoluble iron oxide. It is taken by by every organism as it grows, but algae of all types can take up quite a bit and are the species that most commonly appears to suffer from depleted iron. Some folks, for example, had macroalgae that had been pale and yellow (such as Caulerpa species) turn into lush green growth with iron additions.

Iron also is likely bound to organics in reef aquaria, and those organics can be skimmed out or bound to GAC. Bacteria take up iron as they grow, so organic carbon dosing will also boost the loss rate of soluble iron.

What form of iron are you dosing? FWIW, I have a DIY that I recommend using Fergon tablets from the drug store, if you are interested.

As to your question to consumption rate, that is not really able to be answered because there is no easy way to measure iron at the levels that are usually dosed, and so almost everyone doses without knowing the exact depletion rate. The rate you observe may not be true consumption at all, but mostly precipitation and other abiotic removal mechanisms.

This has more:

Chemistry And The Aquarium: Iron In A Reef Tank ? Advanced Aquarist | Aquarist Magazine and Blog

Chemistry And The Aquarium: Iron: A Look At Organisms Other Than Macroalgae ? Advanced Aquarist | Aquarist Magazine and Blog

from the first one:

Iron in Reef Tanks: How Much and What Form?
Deciding how much iron to add is fairly easy because, in my experience, it doesn't seem to matter too much. Presumably, once you add enough to eliminate iron as a limiting nutrient, extra iron does not apparently cause harm (at least that I've detected in my tanks or heard of from others). I selected a dose of about 0.1 to 0.3 mL of a solution containing 5 g of iron (as 25 g of ferrous sulfate heptahydrate) in 250 mL of water containing 50.7 g of sodium citrate dihydrate. This liquid is dosed 2-3 times per week to my system with a total water volume of about 250 gallons. This iron(II) citrate has turned brown and cloudy since I first made up the bottle years ago, suggesting that it is oxidizing to iron(III) and some is precipitating from solution, but I still use it. Over the past 4 years, I've dosed nearly all of the 5 grams of actual iron to my tank.

Now that may sound like a huge amount, and it is. It's enough to bring 800 million gallons of completely depleted seawater up to the 0.000006 ppm level that I mentioned earlier for natural sea surface water. Still, I've not noticed any problem, do not know the steady state concentration, do not know how high of a solution concentration is actually optimal for my tank, do not know how much is biologically available by the mechanisms mentioned below, do not know how fast it is removed by skimming and other mechanisms, and do not know what would happen if I cut it back by a factor of 1,000.

All that I know is that microalgae has never been a problem since starting the iron, and I've not noticed anything negative that I could attribute to the iron (nor have I heard of any from others doing similar dosing). Still, I don't keep all organisms available to the hobby, and if you do seem to get a negative reaction from something, I'd advise backing off on the dose or stopping completely.

Since many hobbyists do not have access to the chemicals required to make iron(II) citrate, I'd advise buying a commercial iron supplement. There are a number available that seem appropriate and are not very expensive. Some commercial supplements combine manganese with iron (such as Kent's product), presumably because the scientific literature has demonstrated that phytoplankton also scavenge manganese from the water column. I've not experimented with manganese, but it is probably fine to use if you cannot find a pure iron supplement.

I'd also advise using only iron supplements that have the iron chelated to an organic molecule. The iron sold for freshwater applications is sometimes not chelated because free iron is more soluble in the lower pH of freshwater tanks. I'd avoid those products for marine applications. It will likely still work (as many of the studies in the scientific literature use free iron in seawater), but probably not as well because it may precipitate before it has fully fortified the system with iron.

In many cases of iron intended for the marine hobby, the product may not tell you what the iron is chelated with, in order to protect proprietary formulations. I don't actually know if it matters too much. Very strong chelation by certain molecules will actually inhibit bioavailability by not permitting release of the iron without completely taking apart the chelating molecule, but I expect that manufacturers have avoided those molecules. EDTA and citrate, and some others, actually degrade photochemically, releasing small amounts of free iron continually. It is believed to be the free iron that is actually taken up by many organisms, and likely iron(II), though some organisms may be able to convert iron(III) to iron(II) before uptake (the detailed absorption mechanisms are generally not known). There is a more detailed discussion of this degradation and uptake in "Captive Seawater Fishes" by Stephen Spotte (1992).

 

[Tenshoa]

Well this certainly puts a different spin on things. First let me start of by saying thank you for the very informative post.

Previously, I had not dosed trace elements and since a select few of my corals appeared pale, I decided to give a stab at Red Sea's Coral Color program. In addition to the supplements, I also purchased the test kit that goes along with it. Unfortunately, the kit does not measure FE anywhere near a resolution capable of reading the quantities you mentioned. The test kit measures in increments of 0, .05, .15, .25, .35, and .5 indicating that .25 and above is too high and .05 and below is too low. The amount I was having to dose to .15 was depleting to 0 on my test kit within 3-4 days time.

Based on the information you gave, their figures are severely skewed. However, they do raise a few additional questions. Is there a consumer grade test that can measure the amounts of FE you had mentioned? Even if I dosed a much smaller amount, the question of its rate of depletion would still concern me (unless that time frame seems reasonable to you), even at much lower levels. With all things being relatively equal, is it still safe to assume that the coloration I experienced was at least partially due to the addition of FE? For instance, I saw colors on some of my rainbow acros begin to appear that the coral had not previously had (but were supposed to), such as yellows.

I noticed no I'll effects from dosing in that quantity. Macro algae growth seemed to stay the same. No appearance of Cyano or algae elsewhere in the tank, with the exception of film on the glass which also did not appear to be more frequent. It is important to note, based on the information you provided, that I do in fact dose vinegar (used in conjunction with Kalk to strengthen it), as well as a Carbon reactor and a separate reactor that contains Rowa Phos.

It is also worth noting that since Red Seas FE supplement is in liquid form, that it does in fact have a brownish appearance, which if I am not mistaken by your post, would indicate FE III (I assume less effective/usable). Which begs the question, based on what seems to be a considerable number of variables and obstacles pertaining to iron, what else could have contributed to what I witnessed?

I'd like to point out that I perform water changes very infrequently as my import/export of nutrients stays well balanced. I am intrigued by the information that Ehsan Daskti provided in his argument against WC. But that's a conversation for another time.

Lastly, I would be interested in making my own FE supplement so any additional information would certainly be helpful. Would you mind explaining the reason that YOU dose FE?

 

[Randy Holmes-Farley]

No, there is no kit that can detect NSw levels of iron, nor even my recommended dose.

the ICP method that some use (e.g., Triton) cannot detect NSW levels, but likely could detect the amount I dose (at least soon after dosing).

I dose iron primarily for macroalgae (Caulerpa racemosa), which I grow in my refugia.

here's a DIY:


I dissolve 1 Fergon tablet in about 20 mL of RO/DI (actually allow it to disintegrate first, then shake it up).


Then I let the solids settle out, and use the clear greenish liquid.


Dose is very noncritical for iron. I add 1-2 mL once or twice a week to my 120 (~300 gallons total water volume).


"Which begs the question, based on what seems to be a considerable number of variables and obstacles pertaining to iron, what else could have contributed to what I witnessed?"

Which observation?

 

[Tenshoa]

No, there is no kit that can detect NSw levels of iron, nor even my recommended dose.

the ICP method that some use (e.g., Triton) cannot detect NSW levels, but likely could detect the amount I dose (at least soon after dosing).

I dose iron primarily for macroalgae (Caulerpa racemosa), which I grow in my refugia.

here's a DIY:


I dissolve 1 Fergon tablet in about 20 mL of RO/DI (actually allow it to disintegrate first, then shake it up).


Then I let the solids settle out, and use the clear greenish liquid.


Dose is very noncritical for iron. I add 1-2 mL once or twice a week to my 120 (~300 gallons total water volume).


"Which begs the question, based on what seems to be a considerable number of variables and obstacles pertaining to iron, what else could have contributed to what I witnessed?"

Which observation?

Why did my coloration improve so drastically suddenly?

 

[Randy Holmes-Farley]

Well, if it is only related to the iron dosing and not anything else you did, then either the organisms were iron deficient, or something else came in with the iron, such as other trace elements, or possible even organics that are in it.

FWIW, I cannot really recall anyone previously ascribing significant coral color improvements to iron dosing that they started.

 

[Tenshoa]

At first, I suspected an iron deficiency. But now, not being able to test at a higher resolution, I'm not so sure. Would you mind if I inquired about what other trace elements you dose and what trace elements have greater effects on pigmentation?

 

[evolved]

FWIW, I cannot really recall anyone previously ascribing significant coral color improvements to iron dosing that they started.

Justin Credible brought it up in his MACNA presentation this year and raved about his results dosing iron. Specifically the improvement in green coloration.
When asked about dosing amounts, he made a pouring motion (which was in mirror to Rich Ross' earlier presentation in regards to how he feeds) and stated it's kinda whenever he remembers.

 

[Randy Holmes-Farley]

Justin Credible brought it up in his MACNA presentation this year and raved about his results dosing iron. Specifically the improvement in green coloration.
When asked about dosing amounts, he made a pouring motion (which was in mirror to Rich Ross' earlier presentation in regards to how he feeds) and stated it's kinda whenever he remembers.

Thanks.

 

[joaocdestro]

Why did my coloration improve so drastically suddenly?

What is you veredict about dosing iron X Coloration?

 

[Holy_makerel]

Zombie thread but i'm researching this as a possible supplement to add. I started looking into Fe because I watched this presentation by Justin Grabel on coral grafting (really interesting, i suggest watching it). Near the end he talks breifly about iron dosing in conjunction with peroxide dosing and it's interaction with GFO. He spoke highly of the benifits.


Curious if anyone has any information on this? It has piqued my interest.

 

[jason2459]

Thanks for the bump and info in this thread. It does line up with what I've seen since dosing iron consistently through out the day. I've seen colors particularly in my bubble tips to get "bolder". I still do not know if it's the FE or just coincidence. But things do look better.

What I'm dosing, how, and observations.
https://www.reef2reef.com/threads/diy-the-diy-fe-ferrous-citrate-supplement.307168/

 

[Randy Holmes-Farley]

All photosynthetic organisms need iron and it is fairly rapidly depleted in aquaria so is a fine thing to dose. I dosed it for many years.

 

[Randy Holmes-Farley]

FWIW, I don't think his potassium comments at 35:31 make sense. There's no reason to dose it at any particular time of day, and co-dosing with iron does not allow one to maintain higher potassium since it is present at high levels already (400 ppm), hardly depletes at all in the course of one day (not more than 1 ppm per day in most tanks, not at all in many), and can be raised as high as you want with or without iron dosing.

 

[Randy Holmes-Farley]

I disagree with his assertions about the interactions between peroxide, organics, iron, GFO, and skimming. I don't disagree with any practical effects he actually observes, but his hypothesized interactions do not seem correct, and there's no evidence that they are correct. For example, that dosed iron ends up binding to the GFO and that this extends the useful life of the GFO.

 

[jason2459]

I have had no need to dose potassium as of yet with levels consistently over 400. But I also do around 1% daily water change and feed a lot.

Also, I would avoid things like peroxide.

 

[Holy_makerel]

@Randy Holmes-Farley @jason2459

Thank you both for your insights into this subject. I bought kent marines Fe and manganese supplement yesterday because i knew i wanted to start dosing some iron into the tank but wanted to do some more research before starting. My system is a 60 cube mixed reef with a 10 gal sump so approx 55-60gal, running GFO/carbon and cheato reactors.

The kent product recommends 5ml a week per 50 gal but that seems a little high to me. Opinions?

 

[Randy Holmes-Farley]

5 mL of 0.24% Fe (0.0024 g/g or 2.4 mg/mL) solution contains 12 mg of iron.

50 gallons is about 189 liters, so that's 12 mg/189 L = 0.06 mg/L = 60 ug/L.

I typically dose 1-2 ug/L and think that plenty. I do not know if there's a significant drawback to dosing more or not.

 

[jason2459]

I am dosing around 0.1-0.3ml per day with total system volume of 220 gallons. That alone gave instant results. I have not tried anymore then that as my goals for my algae scrubber is met by that small amount and I see deeper coloration as well.

 

[Holy_makerel]

5 mL of 0.24% Fe (0.0024 g/g or 2.4 mg/mL) solution contains 12 mg of iron.

50 gallons is about 189 liters, so that's 12 mg/189 L = 0.06 mg/L = 60 ug/L.

I typically dose 1-2 ug/L and think that plenty. I do not know if there's a significant drawback to dosing more or not.

Thank you for the calculation Randy! So looking at that and per your 1-2ug/L dosing suggestion if i dosed 0.15ml of the product a week(or should this be daily?) i would be adding 1.8ug/L of Fe to the system.

Sounds like a good place to start. Thank you!