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Discussion Starter · #1 · (Edited)
While researching an issue I was having, I happened to come across this article - http://www.americanaquariumproducts.com/Redox_Potential.html - The Rexox Potential (ORP) in Aquariums & Ponds, How it relates to Good Aquatic Health: Effect of water changes, DOC, UV Sterilization, mineralization on a healthy Redox Balance, byt Carl Strohmeyer.

If this article is true, in whole or in part, then Redox (even if it is tricky to measure), is a a very significant water parameter which I'd basically been ignoring at my expense and peril! I thought Redox was mostly a concern for reef aquariums, but supposedly it happens to greatly underpin the very health and success of our freshwater systems and explains a great many things which other water parameters do not.

It seems the author has its detractors on this, such as Tom Barr, but I wasn't sure if that was a disagreement over just certain aspects of the argument or the entirety of it. Tom seems more concerned with the Redox of the substrate for plant health, at the peril of misquoting him based upon having seen some comments of his thus far. He has one or more articles on his report so I should perhaps really get around to subscribing to that now, but which I haven't in any case done so for.

The author has in any case clearly put a great deal of thought and attention into this matter and seems relatively convincing, though there are certain points which I'm also questioning. Then I also found this article which differs somewhat in its recommendations - http://www.koiclay.com/page6.htm

Apparently Redox is a more or less clear indicator of the health of your system and the amount of organic pollution in it with a range between 250 and 400 being desirable. And Redox can be raised by many means including: oxygenation via aeration/flow, removing organic matter, lower stocking levels, water changes, biofiltration?, activated carbon, adding 'fresh' calcium and magnesium, ozone, UV Sterilizers. I have to assume that healthy plants raise Redox levels as well though. Nevertheless, is Redox as discussed in the first article supposedly the key reason why you'd want to have regular water changes and low fish stocking levels, regardless of how low your nitrates are. But are plants a better biofilter than bacteria, as they'll raise Redox more than bacteria do?

And thus, if you have low Redox you'll be more likely to have problems with both algae and fish diseases? Carl's article sounds rather different than the suggestions put forth by Diana Walstad, who seemed perfectly fine with having high DOC, although it might explain why she also suggests maintaining low stocking levels. But then there is also the first article's discussion over Redox balance, which suggests that lower Redox levels than 300 aren't bad actually, but I'll still need to get my head around some of that and reread things through.

I did happen to order some wonder shells from Amazon.com now to try out, although it also now seems that a bag of aragonite or crushed dolomite added to the filter would have also worked. But as I'm not trying to maintain hard water I might need to stick a decent amount of peat into the filter to buffer the alkalinity of those?

And apparently it seems that the use of ozone or a UV sterilizer would greatly help the help of my/our systems by raising the Redox, (so long as controlled properly in the case of ozone to not raise the ORP too high). It sounds as if UV sterilizers are much easier and safer to use though, and help maintain very clear colorless water by also oxidizing whatever DOC's/tannins/etc pass through them.

Please advise! And thanks in advance!
 

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The SW hobby went through a time where redox and ozone were quite the "in thing". While it's still used by some, it's not the be all, end all thing it was once considered. I found the article good, but IMO it's not worth worrying about redox, and related items such as ozone, unless you have a very specific issue to resolve that can not be solved by other means such as water changes.

If you are going to consider ozone, keep in mind that this can be an expensive investment. Also, it must be used safely. See this article (offsite) - http://reefkeeping.com/issues/2006-04/rhf/index.php

Having used both UV and ozone, again in SW systems, I'd say that ozone does a lot more than UV as far as raising redox and keeping water clear, removing tannins and so on.

Perhaps the best question is, what is the issue your trying to solve? Ozone or UV might be a solution, but often you can get results without the investment in additional equipment.
 

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Discussion Starter · #3 ·
It's not a single issue or goal. I wish to attain optimal water chemistry for the fish and plants. Lessening the need for water changes, or at least ensuring that water quality does not decline between water changes is something I'd certainly like to achieve as well as my time too is finite. And I don't want to be naive about my tank's ecology and water parameters and just follow practices blindly, so I do want to understand these things as thoroughly as I can.

I appreciate there had been an ozone bandwagon which a lot of people jumped on until they apparently got distracted by something else, but that doesn't demonstrate whether or not it was a good idea.

I was opposed to the idea of UV sterilizers as being unnecessary generally until I found they actually do impact the redox, and seem easier to use in any case than ozone. If they're not that effective at raising redox then perhaps they're not worth it in comparison. But if either does have a significant impact in terms of ensuring high water quality is maintained even as a precautionary measure then I'd prefer to use one for my next project.
 

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It's not a single issue or goal. I wish to attain optimal water chemistry for the fish and plants. Lessening the need for water changes, or at least ensuring that water quality does not decline between water changes is something I'd certainly like to achieve as well as my time too is finite. And I don't want to be naive about my tank's ecology and water parameters and just follow practices blindly, so I do want to understand these things as thoroughly as I can.

I appreciate there had been an ozone bandwagon which a lot of people jumped on until they apparently got distracted by something else, but that doesn't demonstrate whether or not it was a good idea.

I was opposed to the idea of UV sterilizers as being unnecessary generally until I found they actually do impact the redox, and seem easier to use in any case than ozone. If they're not that effective at raising redox then perhaps they're not worth it in comparison. But if either does have a significant impact in terms of ensuring high water quality is maintained even as a precautionary measure then I'd prefer to use one for my next project.
I agree we shouldn't follow practices blindly. And I found it odd that there's virtually no mention of redox potential on this forum.

What we do is for some just a hobby, but it shouldn't be because what we are really doing with planted tanks is underwater horticulture and just like terrestrial horticulture it should not be a guessing game. I found another article on the subject. It's more current.
REDOX (REDOX POTENTIAL) BASICS (OXIDATION POTENTIAL, ORP):

http://www.americanaquariumproducts.com/Redox_Potential.html
 

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Discussion Starter · #5 ·
I agree we shouldn't follow practices blindly. And I found it odd that there's virtually no mention of redox potential on this forum.

What we do is for some just a hobby, but it shouldn't be because what we are really doing with planted tanks is underwater horticulture and just like terrestrial horticulture it should not be a guessing game. I found another article on the subject. It's more current.
REDOX (REDOX POTENTIAL) BASICS (OXIDATION POTENTIAL, ORP):

http://www.americanaquariumproducts.com/Redox_Potential.html
Was there supposed to be another link there to another article which didn't work? The only link was to the same main article I was talking about at the beginning.

That was the article that talked in some detail about the ionization and magnetization of water, which was what had been dismissed by others as quackery. It all leaves you a little unsure about exactly what we should be believing though.

If redox is that fundamental a parameter then I'm a bit annoyed that I hadn't heard about it before in any detail, so agreed that it's odd if it has so little mention. But it means I should make some modifications to my practices including increasing oxygenation via surface turbulence, and indicates that perhaps I may have not ideal levels of redox considering my ratios of flora/fauna bio-density.

But more to the point, is Redox the supposed mysterious reason to actually do water changes? (In case that other parameters such as nitrates were low and in case we're not doing EI)?
 

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If you're that obsessed with water quality build a foam fractionator (giant FW skimmer basically) and save yourself some headache and risk.
 

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It's a hobby! So, you "should" do whatever enhances your enjoyment of the hobby. If that includes playing with/measuring/ using REDOX by all means do so. If you just want an attractive healthy planted tank, it isn't necessary to even know what REDOX stands for. All I ask is that you share your knowledge, and findings with us, to enhance our enjoyment of the hobby.
 

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Was there supposed to be another link there to another article which didn't work? The only link was to the same main article I was talking about at the beginning.

That was the article that talked in some detail about the ionization and magnetization of water, which was what had been dismissed by others as quackery. It all leaves you a little unsure about exactly what we should be believing though.

If redox is that fundamental a parameter then I'm a bit annoyed that I hadn't heard about it before in any detail, so agreed that it's odd if it has so little mention. But it means I should make some modifications to my practices including increasing oxygenation via surface turbulence, and indicates that perhaps I may have not ideal levels of redox considering my ratios of flora/fauna bio-density.

But more to the point, is Redox the supposed mysterious reason to actually do water changes? (In case that other parameters such as nitrates were low and in case we're not doing EI)?
My mistake with the link. Ignore it.
 

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Discussion Starter · #9 ·
It's a hobby! So, you "should" do whatever enhances your enjoyment of the hobby. If that includes playing with/measuring/ using REDOX by all means do so. If you just want an attractive healthy planted tank, it isn't necessary to even know what REDOX stands for. All I ask is that you share your knowledge, and findings with us, to enhance our enjoyment of the hobby.
Fish are happy, I'm happy. Fish get a disease, fishkeeping's then not so fun. ;)

Hoppy, in researching this topic I also came across your RFUG with CO2 thread from a few years back, which was quite interesting for me as I was just considering trying some similar things. Do you think there is any way to do that in combination with using MTS though? I really do want to try the idea of CO2 in the substrate, even if I happen to have very minimal water flow through it or maybe just a recirculating loop that I'm bubbling CO2 into. I'm not sure how to do that in combination with soil though, maybe covering the piping with a sheet of foam first, which the CO2 could bubble into and be held by or something. (How is that for hijacking my own thread!).
 

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Fish are happy, I'm happy. Fish get a disease, fishkeeping's then not so fun. ;)

Hoppy, in researching this topic I also came across your RFUG with CO2 thread from a few years back, which was quite interesting for me as I was just considering trying some similar things. Do you think there is any way to do that in combination with using MTS though? I really do want to try the idea of CO2 in the substrate, even if I happen to have very minimal water flow through it or maybe just a recirculating loop that I'm bubbling CO2 into. I'm not sure how to do that in combination with soil though, maybe covering the piping with a sheet of foam first, which the CO2 could bubble into and be held by or something. (How is that for hijacking my own thread!).
I don't think it will be possible to use a RFUG with MTS or any fertile substrate. But, you could isolate one section of substrate in a large tank, and have a RFUG there. One of our regulars in India uses that method for filtering, except just a regular undergravel filter - isolated to a small area of the substrate. If the substrate is loaded with nutrients, circulating water up through that substrate might overload the water with the nutrients.
 

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I did RFUG 20 years.............

Redox should be quite high in any FW tank, about 400.

Few bother with it.

It's a sediment parameter.

DO(dissolved oxygen) is better for FW if you want to monitor some parameter related to the health of the plants/fish. :icon_idea
You like wild goose chases, go after a few of them Canadians please.
 

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Fish are happy, I'm happy. Fish get a disease, fishkeeping's then not so fun. ;)

Hoppy, in researching this topic I also came across your RFUG with CO2 thread from a few years back, which was quite interesting for me as I was just considering trying some similar things. Do you think there is any way to do that in combination with using MTS though? I really do want to try the idea of CO2 in the substrate, even if I happen to have very minimal water flow through it or maybe just a recirculating loop that I'm bubbling CO2 into. I'm not sure how to do that in combination with soil though, maybe covering the piping with a sheet of foam first, which the CO2 could bubble into and be held by or something. (How is that for hijacking my own thread!).
Vascular aquatic plants have a process called guttation. This creates a very slow flow through the substrate.
 

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Discussion Starter · #13 ·
Okay, so whether it's DO or Redox, and regardless of whether we measure it even, the principle remains the same that for the health of our fish it is important that we should plan our systems to aim for relatively high values, right?

And that a UV sterilizer will help with that, with an ozonizer helping even more, correct?

Apart from that, how much stock should I generally put in the Redox article by Mr. Carl Strohmeyer?

In terms of the RFUG it's simplyabout creating a CO2 rich plenum under the plants, not to utilize it for filtration or flow (which I'd aim to keep very minimal actually), though there are questions about whether CO2 there would work for the plants.
 

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The easiest way to keep a high level of dissolved oxygen in the water is to maintain good water surface ripple over the whole water surface. When I used my RFUG I hoped to get better distribution of CO2, and by doing that, get less BBA. It didn't make any difference in that regards, as far as I could see. But, the water clarity was outstanding. Most of my filtering then was done with a canister filter, with it's output going to the RFUG.
 

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Discussion Starter · #15 ·
Trying to draw some conclusions now, it seems that Redox is a combination of different factors - organic pollutants in the tank/oxgen levels/calcium and magnesium levels/etc. So similar to how ph which is a affected by various factors including minerals/acids/CO2 in the tank, Redox isn't an exact science or an altogether clear thing to measure. And perhaps it is rather a crude indicator of organic pollutant levels, but somewhat an indicator nonetheless. But even if we don't know or need to know specific Redox levels, that doesn't mean we can't do things to raise the Redox.

Thus, in terms of removing those organic pollutants indicated by low Redox levels, we can generally handle those either of two ways in case our plants aren't doing it sufficiently. We can do do either water changes, or we can use ozone/UV sterilization, but both manage to equally accomplish the same thing in terms or lowering organic pollutant levels and thus raising Redox, is that correct?
 

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I would like to resurrect this thread with the following paradox:
I have a very small tank (3G = 12L) with lava stones and akadama as a substrate. I put there (into the substrate) a really big amount of fertilizer for terrestrial plants also, so after I filled it with water I had more then 150 mg/L NO3 (confirmed laboratory analysis). Also I use LED light with more then 100 µmol PAR at the substrate level (and around 150 µmol PAR at water surface). All the tank is full of algae, which is no surprise under these circumstances. But, what surprises me a lot are two things:
1) COD is very low (<0,5 mgO2/L)
2) ORP is extremely high (+510 mV, and each day keeps increasing!)
According to what I have read concerning algae and ORP (redox), in the tanks where there are algae problems, the organics should be high, and ORP should be low ... but that's not the case with my tank.

Is there anybody who can explain this to me?


According to this post: barrreport.com, such a high values as I have should be dangerous for fish, so how can that be that in my tank the ORP is so high, although I do not add anything in there (except a small doses of liquid carbon, as I don't use pressurized CO2 there). I don't use any fertilizers, and I have only a very small HOB filter there.

PS: The tank is about 2 months old. You can look at it here: www.prirodni-akvarium.cz (test #3).
 

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Just Tryin' to Make a Living-Times Are Tough...

Hi Marcel,

In as much as you have 150-mg/l (ppm) Nitrates and are not fertilizing that means that ammonia/ammonium is coming from somewhere.

I am sure the terrestrial fertilizers are producing the ammonia/ammonium, beyond what the algae can consume and your biological filtration in this case just happens to include algae and will continue to do so until the excess nutrients are consumed (exported).

You are providing a lot of light and no creatures to add organic material to the water so it is extremely clean. Getting close to a level that could harm the critters keeping it so clean.

More later, I have some real life issues I am dealing with at the moment.

Respectfully,
Joe
FBTB
 

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Hi Joe,

yes, the source of such a high nitrates is for sure the terrestrial fertilizer which is leaking through the substrate into the water column. I can fix that, but I would like to test this unusual environment, so I just let it be ... not doing anything with it for now. As there are no critters I need not worry. There are just some indestructible snails.

I was just curious why could it be that I have such a high ORP in there + a lot of algae at the same time ... because according to the table on barrreport.com at such a high ORP the environment should be algae-unfriendly.

Marcel
 

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Cycles

Hi Marcel,

Yes, with the ORP values climbing into the 500-mV ranges for sustained periods of time, the water is becoming an increasingly hostile environment for the microbes, what you have is nature’s version of added hydrogen peroxide. These really is no paradox, your system is working hard to find equilibrium.

You have a young system with a tremendous amount of added energy (lights mainly), extreme nutrient load, nowhere near enough plants to consume/export the nutrients.

I would say it also makes me think the tank temperature and pH are likely (relatively) low.

Best guess is the HOB filter is “slimy,” a good load of biofilm, this is the protection for the microbes from the oxidizer. I would assume the same would be true at the substrate surface. The lava rock provides an excellent environment for the nitrifying bacteria. The algae is consuming a great deal of nutrients and producing a good deal of oxygen, in fact, producing hydrogen peroxide.

I am assuming COD test with potassium dichromate (best) or potassium permanganate (okay) with the excess oxygen estimated by titration.

The problem with COD (chemical oxygen demand) as an indicator in this case is the high oxidation level of the solution, would seem to be an interference.

I like that you are allowing this to proceed, I have done this a couple of times but at half (or less) the light you are using. In each case, the tanks went through a “crash,” then recovered and went on to be stable systems.

Our aquariums do not really cycle, s in the neat way the advertisers would have us think; there are several cycles, really, it is closer to waves. In systems not reasonably balanced, they simply have a more dramatic way of achieving equilibrium.

Respectfully,
Joe
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Hi Joe,

the temperature is somewhere around 22°C (72°F), so it's low. The pH is ~5.4, so also very low. I know this environment is not good for microbes. In normal case I won't allow the tank to have such a hostile conditions too long. Normally I do my best to up the temperature and pH, and have a reasonable level of oxygen for microbes to work effectively, so that the tank can stabilize as soon as possible. But as I already said, I did not understand the high ORP values. You say that the reason is probably algae producing hydrogen peroxide. I have to say I did not know that algae can produce H2O2, but that would explain a lot.

Still, that lead me to another question:
Why I do not have such a high ORP values in my second tank, where there is even stronger light (around 120 µmol PAR at the substrate), and much more plants? I have another 15G tank with quite efficient canister filtration, CO2 supply, ADA Aqua Soil substrate, only 10 little sakura shrimps ... where the ORP is between +350 to +400 mV. There are virtually no visible algae. But why the redox do not go as high as in the small 3G tank? Do you think that algae produce more H2O2 then plants (if both has about the same biomass)? Or does filtration or water movement "outgass" the H2O2 (as in the bigger tank I use better filtration and ripple the water surface, unlike the smaller one)? Or do I "reset" the ORP each time I change water in the bigger tank ... so if I stop doing water changes, the ORP will finally come to similar values as in the smaller tank (where I don't do water changes as often)?

Thank you, Joe, for your comments.

Marcel
 
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