What is a good ORP/Redox value?

Gilles

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I currently have loads of algue and ~100mv Redox. So i did some changes:
- Installed a new co2 reactor (the sera one) and saw my flow in my Eheim 2080 increase by ~25%.
- Installed an additional filter, the Eheim 2250

So i am now thinking that i have to much OM which is causing my redox to drop to far.

So increasing my redox is the next step! But i am unsure how high it must be.
 

yme

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I don't know either....

but what I do notice is that adding loads of traces in my tank lowers the the redox by 100.
for what it is worth: before adding traces I measure 280, after adding traces I measure 180. the next day the redox is again 280.

I also kind of wonder whether reducing the redox by adding such an overkill of traces is a good/ bad/does matter thing.

no idea :)

yme
 

Gilles

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reducersoxidizers4.jpg

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

Biollante

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Orp

Hi,

I am always reluctant to answer this question, as it seems to anger many folks. :( I am not trying to anger anyone, I am what I am and these are my observations. http://www.angryflower.com/biolla.gif

For those who do not approve of regular folks using electronic devices, pretend the values were derived by chemical or olfactory means. :gw

{ORP in the water column alert, Plant Guru Team, please avert your eyes.}

I believe ORP values of 280-380-mV are excellent. :gw

A number like -100-mV is worrisome to say the least; I would expect to see in substrates, not the water column.

Are you reasonably sure, your meter and/or sensor is operating properly?

{Most of this is based on Chris Walster’s excellent article in the Summer 1997 issue of Koi Health Quarterly, the numbers below or based on my observations so any errors are mine}

  • 700-750-mV sterilizes water in 20 minutes or so, a good number for swimming pools.
  • 575-700-mV results in serious harm to fish within 10 minutes or so.
  • 475-550-mV high-level use of Potassium permanganate kills parasites, destroys (oxidizes organic products); an excellent way to clean pipes and tubing, turn off filtration, this level will severely damage or destroy biological filters. Fish exposure should be limited to a couple of hours per week.
  • 400-450-mV often accomplished with the use of Potassium permanganate or ozone, though I have a 450-gallon tank that routinely exceeds 430-mV for a couple of hours a day and several others that reach 405-420-mV daily. Snails and a number of other critters do not do well in these tanks.
  • 280-400-mV is very good to excellent water quality, excellent fish health, great plant growth little algae some primitive plants have problems in the upper end of this range. Snails do not do well above 320-mV or so.
  • 200-260-mV green water, slime (bio-films) and so forth, fish health is compromised, fish losses increase and snails breed wildly. UV-sterilization really helps. (Though Potassium permanganate, massive water changes and cleaning the dad-gummed filters makes a lot of sense.
  • 150-200-mV nasty, algae, slimy goo, smells bad, major work required, fish health is poor.

I do not know if this helps.

Respectfully yours,
Biollante
 

Gilles

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Hi Biollante, that actually helps a lot, you never offend me, i learn a lot from you :p

I was surprised to see that adding an air"stone" (Sanders type 2) boosted my Redox from 100mv to 300mv in 2 days (without ozone!). But it actually makes sense since it does gas exchange. Now i might have the answer to why the Belgium guys with a sump get such good tank results. They have a good redox ;)

Today i switched on ozone (2.5mg/hour unit) to push ORP to 375mv, that is my target goal...

I must admit that when the meter was pointing to 100mv it was a new electrode, and newly inserted into the column. I heard that these redox things always take time to acclimate, so the redox might actually be around 300 all the time...
 
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pepetj

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Biollante;55805 said:
Hi,

I am always reluctant to answer this question, as it seems to anger many folks. :( I am not trying to anger anyone, I am what I am and these are my observations. http://www.angryflower.com/biolla.gif

For those who do not approve of regular folks using electronic devices, pretend the values were derived by chemical or olfactory means. :gw

{ORP in the water column alert, Plant Guru Team, please avert your eyes.}

I believe ORP values of 280-380-mV are excellent. :gw

A number like -100-mV is worrisome to say the least; I would expect to see in substrates, not the water column.

Are you reasonably sure, your meter and/or sensor is operating properly?

{Most of this is based on Chris Walster’s excellent article in the Summer 1997 issue of Koi Health Quarterly, the numbers below or based on my observations so any errors are mine}

  • 700-750-mV sterilizes water in 20 minutes or so, a good number for swimming pools.
  • 575-700-mV results in serious harm to fish within 10 minutes or so.
  • 475-550-mV high-level use of Potassium permanganate kills parasites, destroys (oxidizes organic products); an excellent way to clean pipes and tubing, turn off filtration, this level will severely damage or destroy biological filters. Fish exposure should be limited to a couple of hours per week.
  • 400-450-mV often accomplished with the use of Potassium permanganate or ozone, though I have a 450-gallon tank that routinely exceeds 430-mV for a couple of hours a day and several others that reach 405-420-mV daily. Snails and a number of other critters do not do well in these tanks.
  • 280-400-mV is very good to excellent water quality, excellent fish health, great plant growth little algae some primitive plants have problems in the upper end of this range. Snails do not do well above 320-mV or so.
  • 200-260-mV green water, slime (bio-films) and so forth, fish health is compromised, fish losses increase and snails breed wildly. UV-sterilization really helps. (Though Potassium permanganate, massive water changes and cleaning the dad-gummed filters makes a lot of sense.
  • 150-200-mV nasty, algae, slimy goo, smells bad, major work required, fish health is poor.

I do not know if this helps.

Respectfully yours,
Biollante

This proposal have been challenged for a couple of years.

I keep my FW planted with fish tanks (15 of them) within a range from -110mV to +135mV). I aim at the -100mV to +50mV range but haven't got there yet. I don't tamper water parameters to adjust REDOX per se, I just make readings of this variable as I attempt to "fine tune" my target range of other water parameters (mostly pH, KH, GH, TDS, dissolved CO2, dissolved O2).

I use a Hach ORP pocket meter (no calibration possible but reference solution used to assess its accuracy).

The chart comes from http://www.water-prox.com/mineral_redox.htm. Unfortunately their "research" lacks citations, nevertheless this information seems to make sense (low ORP = Health).

It was through Carl Strohmayer articles (American Aquarium Products) that I came across this proposal for the first time, in late 2008.

Pepetj
Santo Domingo

deox-chart12.jpg
 

Biollante

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Hmmm...

Hi Pepetj,

My experience is what it is. :eek:

The numbers you cite are closer to what I would expect an inch or so (3 cm) deep in substrate. :confused:

I have also tested natural waters where many of our fish come from and found them to be consistent with my “pollution” index.

I will read the material and see what I can make of it.

I started out with a pocket (used, cheap) ORP/pH pen and moved up to a Hach pocket meter and on to high end ORP meters and for the most part I find the readings reasonably consistent (with due care and use of reference solutions). :cool:

Biollante
 

Yo-han

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Bringing up this old thread because I measured ORP in quite some tanks now. Tanks that did great and tanks from clients that were algae infested or had a lot of trouble with fish health. All tanks I considered healthy (healthy fish, no nasty algae) had ORP values of 260-300 mV. Tap water is around 240 in this area and all unhealthy tanks had ORP values below 265.

But I read two contradictory things. A high ORP is good to oxidize organics, parasites etc. But at the same time I learned (more human related) that a negative ORP is better (like a lot of anti-oxidants) to prevent free radicals destroying the good things in your body. Who can explain these two contradictory statements and help me understand redox better?
 

Tom Barr

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Internal suppression/control, regulation of oxidized radicals(super oxide etc, singlet oxygen species etc etc) vs external and a source of O2 for respiration.

We need good O2 for plant growth, cycling, sort of a measure of COD/BOD.

Redox is rarely used much for the water column for freshwater.
It is used mostly for the sediment conditions in aquatic wetland soils.

Marine systems, for control of O3.
 

Yo-han

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But at the same time we need to keep organics low, oxygen high, tank pristine, isn't that like saying you need to keep ORP high?
 

Tom Barr

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Yo-han;114733 said:
But at the same time we need to keep organics low, oxygen high, tank pristine, isn't that like saying you need to keep ORP high?

Sort of, but good plant growth/care does this.

You can always add Ozone if you think it's important:)
 

marc1973

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Hi all. Great site. Very helpful post. Can I please ask are the mv range,s above the same for a saltwater aquarium please. Thanks in advance.
 
I appreciate this thread. I have a group of planted aquariums that are networked.. that is to say they share a common sump, common UV filter, common CO2 injection, common heating and common fertilisation regimen. temp, pH, ORP and other values are measured in the sump.

the tanks are very, very clean. the plants are doing okay, but I've got a long way to go to learning to satisfy them. I maintain a temperature of 27degC and currently a pH of 6.4. (my probe is old and my calibration solutions are expired... so using a test kit.... color is somewhere close to 6.5.... Probe is reading 6.0 (but I don't trust it... new probe and calibrations solutions are on their way).

I'm using 95% RO water. I have an auto-top off.... I'm changing about 25% once a week. Tanks are lightly loaded for fauna, heavy with stemp plants. Amonia, nitrates and nitrites are basically undetectable. ORP reads about 385-395 rather consistently. Seems just on the high end, but I'm not panicking. I will automate the water changes and step it up to about 40% once a week in about two weeks once I've finished the programming.
 
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