Algae and Iron

4599 Views 37 Replies 8 Participants Last post by hoppycalif, May 13, 2020

hoppycalif

Discussion Starter · Jan 22, 2020

Diana Walstad, in her book, "Ecology of the Planted Aquarium", proposes that algae is limited in its growth by the limited availability of iron in the water. She says that while plants can get iron from the substrate, through their roots, algae doesn't have that ability, and has to depend on the iron in the water. Furthermore, that iron in the water has to be bio-available, in the form of soluble ions, Fe2+ and Fe3+. But, those ions have a very brief "life" in water because it easily bonds to various water soluble organic carbon compounds. As a result, algae has a difficult time reproducing unless there is a reliable source of Fe2+ and/or Fe3+ in the water.

One way those iron ions can be reliably available is if the iron that is bound to soluble organic carbon compounds is exposed to lots of light. When that bound iron is exposed to light of adequate intensity and spectrum, the light can cause the iron ions to be released into the water, by a process called photo reduction.

I find this extremely interesting, and one of the most compelling arguments about "why does algae take over my aquarium"? So, I am going to do a simple experiment to try to demonstrate that process.

I have a 10 gallon tank, modified with a divider into two adjacent 5 gallon tanks. The same light fixture lights both halves of the tank. See https://www.aquaticplantcentral.com/forumapc/diy-aquarium-projects/143379-tank-divider.html

If I dose each 5 gallon half of the tank with the same amount of iron (from Flourish Iron), but add the iron as the light comes on for one half, and after the light goes off for the other half, there should be a significant difference in availability of Fe2+/Fe3+ in the two half tanks. I should see more algae growth in the half with the most available iron.

I'm about 2 weeks or so from being ready to start my experiment.

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mistergreen

· #2 · Jan 22, 2020

What's your water pH? That affects the availability of iron too. Below 8.0pH should be fine. Below 6.0 is optimal.

hoppycalif

Discussion Starter · #3 · Jan 22, 2020

I will have to measure the pH when I get closer to starting this. First I need to get a couple of Betta's to occupy the two tank halves. The water is pretty hard, but I forget the numbers right now.

dwalstad

· #4 · Jan 23, 2020

Interesting. Since the pH and water is the same in both tank halves, pH doesn't really matter. There's also no need for fish.

You will have plenty of other confounds and wiggle room in your reporting, so I would keep it simple and do it as a "pilot experiment." If you get a dramatic difference, then you can trumpet your results and we can enjoy hearing about the details and speculations.

If you get no effect, then I could point to not doing experiment in triplicate. Or that both tank halves were exposed to light at some point during each 24 hr cycle. In the published experiment, there was light in each case, but one set had normal light, the other light where all the shorter, more energetic wavelengths (below 520 nm), which create reduced, algae-stimulating iron, had been removed. Algae didn't grow with the shorter wavelengths, but it did with normal unrestricted light.

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hoppycalif

Discussion Starter · #5 · Jan 23, 2020

dwalstad said:
Interesting. Since the pH and water is the same in both tank halves, pH doesn't really matter. There's also no need for fish.

You will have plenty of other confounds and wiggle room in your reporting, so I would keep it simple and do it as a "pilot experiment." If you get a dramatic difference, then you can trumpet your results and we can enjoy hearing about the details and speculations.

If you get no effect, then I could point to not doing experiment in triplicate. Or that both tank halves were exposed to light at some point during each 24 hr cycle. In the published experiment, there was light in each case, but one set had normal light, the other light where all the shorter, more energetic wavelengths (below 520 nm), which create reduced, algae-stimulating iron, had been removed. Algae didn't grow with the shorter wavelengths, but it did with normal unrestricted light.

I agree that this will not prove anything, but I'm just looking to see if, in a normal planted aquarium setting, does big differences in how iron is dosed cause a big difference in algae problems. It has to be a big difference to mean anything at all for me because I find it very hard even with this set-up to get two tanks to act the same. So, the first step has to be finding out just how much variance is "normal". I have no idea what I will find out, other than that the odds are that I won't see any significant difference.

The reason for the two fish is to have something else to enjoy with this odd tank. I will really be embarrassed if one fish survives and the other gets sick.

I enjoy doing this kind of thing!

dwalstad

· #6 · Jan 23, 2020

hoppycalif said:
I enjoy doing this kind of thing!

Excellent! It's fun to investigate as well as enjoy your fish and plants. It provides purpose.

mistergreen

· #7 · Jan 29, 2020

Here's a guy experimenting with a setup similar to yours.

He's testing out fish food vs ferts.

hoppycalif

Discussion Starter · #8 · Jan 29, 2020

Don't look for me to make a Youtube video, after buying a white smock and visiting my barber, and writing a script, etc.

mistergreen

· #9 · Jan 29, 2020

Please put it on youtube!
I expect the video to be in portrait mode and out of focus, maybe with an errant thumb here and there.

hoppycalif

Discussion Starter · #10 · Jan 29, 2020

I now have a Betta in each tank, looking healthy, and both tanks look the same, as far as the plants are concerned. The pH of the tank water is about 6.6-6.8, which I assume comes from the tannins released by the dirt substrate. My tap water has a higher pH.

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mistergreen

· #11 · Jan 29, 2020

How will you test for Fe? This sounds like a tough experiment to work out?
So algae will be your indicator? I wonder if you can collect and dry the algae and burn it and find left over iron.

Stan510

· #12 · Jan 29, 2020

The plants you chose are not the best to show a difference. They really should be plants like Hygrophila or Sagittaria or other all green plants that show a flush of greenness on the iron. Except for Vallisneria..it might even be greener with no iron in the water. Always exceptions.

hoppycalif

Discussion Starter · #13 · Jan 30, 2020

The plants iin the tanks are Sagittaria subulata and a hybred swordplant, plus floating Salvinia. I'm not interested in the effect on the plants, because it is well proven that iron helps the plants. My interest is the effect on algae, primarily on the effect vs the amount of light the iron fertilized water gets. I'm very interested in the idea that iron shortage can inhibit algae growth.

Stan510

· #14 · Jan 30, 2020

Dont use any plants. I can tell you,you can can grow pounds of hair algae in aquariums that never see a drop of IG,plus spot and blue green. A third aquarium with backyard dirt would also feed hair algae. It also minus a drop of iron. MY "Prediction" because I've done it!

Stan510

· #15 · Jan 30, 2020

btw,That sword plant that for the last year,was super struggling to grow 4" leaves? IS IN DIRT. Its one of the first plants I added..I used garden soils and sands..with an inch or so of sand. From,oh, October of 2018- Nov.2019 it came close to dying..I had even just cut off every leaf at one point. Just a bud.
And now....virtually all this since late November.

one more,The last Prof. Scientist I worked for loved the way I wrote my notes I left him. Had a sense of humor did he.

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hoppycalif

Discussion Starter · #16 · Feb 17, 2020

My experiment is starting!! The two tanks are now pretty well established, with no obvious algae, almost exactly the same plants in each, same light, same substrate, and a Betta in each one. Tonight I will start dosing Flourish Iron, to get 0.10 ppm in the water in each tank, dosed after lights out at night, every other night. If all goes well, I will get no obvious algae. After about 2 or 3 weeks, I will change the dosing time for one tank to right after the light comes on.

Now I need a Swiss trolley to ride in so I can get a brainstorm going!!

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mysiak

· #17 · Feb 18, 2020

I'm sorry if I missed something, but Flourish contains Iron gluconate and it is being said to be uptaken very rapidly by plants (or broken down if plants can't fully utilize it). Do plants or algae consume nutrients during night?

It sounds like you're just adding additional step in iron availability:

Dosed with lights on: Iron gluconate -> Iron -> Plants/algae
Dosed with lights off: Iron gluconate -> Iron -> "some other organic Iron molecule" -> (light) -> Iron -> Plants/algae

From what I read, Iron gluconate seems to be so bio-available, that it might be impossible to detect any Iron even 1 hour after dosing during photosynthesis period (unlike other chelators).

But again, maybe I just got the wrong end of the stick.

hoppycalif

Discussion Starter · #18 · Feb 18, 2020

Dosing the iron, in low dosages, at night should cause all of it to be taken in by the plants, or attached to dissolved organic carbon in the water, leaving none for the algae. But, dosing iron as the light comes on may cause the iron attached to organic carbon to be released into the water as Fe ions, if photo reduction occurs with the level of light intensity we use. That would make it more available to algae, as well as to the plants. And, that might cause algae to start growing vigorously. I expect to see no algae response, because I expect that photo reduction is trivial at the level of light intensity we use. I wouldn't bother with this if I had never had an algae problem at low aquarium light levels. It would be very interesting if I do get an algae growth response. Meanwhile, I will be convincing myself that I can get two tanks to grow without algae problems, making additional testing possible.

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mysiak

· #19 · Feb 19, 2020

Thank you for the explanation, but I still must be missing something

Dosing with lights off
- let's consider the "worst" case scenario, all of the Iron will get re-attached from Gluconate to another organic carbon. Once you turn on the lights at certain intensity, Iron gets released and consumed by plants (and algae).
- the best case scenario - all of the Iron is consumed by plants during night. But why not by algae as well?

Dosing with lights on
- Iron gluconate is consumed either directly or broken down rapidly and Iron released and consumed by plants and algae.

Nevertheless interesting setup for experiments. I am curious if you'll see any major difference in plants growth with this different dosing schedule while using Iron gluconate particularly.

hoppycalif

Discussion Starter · #20 · Feb 19, 2020

I don't think you are missing anything. It seems that nothing in an aquarium is a simple thing. I got interested in this when I read about the possibility that algae is handicapped by being able to get iron only from the water, but bioavailable iron in the water is rapidly removed. That made me wonder why algae is such a big problem in aquariums. The photo reduction idea might be a big factor. I will be astonished if I see a major difference with my little experiment, but I will be enjoying trying to do such an experiment, so it doesn't really matter.

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