oxidation reduction potential
This is a misunderstood and difficult subject to understand as it relates to our aquariums.
While doing research for the effects of ozone I found this article that Randy Holmes-Farley wrote, ORP and the Reef Aquarium.
I suggest that you read it as it raises some questions about aquarium water quality and the things we do to control it.
One thing said is that keeping track of ORP is not always necessary, unless you are using O3. It's more about ORP and the use of O3 I would like to focus on, but any insights you have on ORP would be valuable to hear.
A brief summery of ORP: it represents the balance between chemical oxidizers who want to gather electrons, and chemical reducers who want to get rid of their electrons. This balance is always changing, and is effected by so many different variables it is impossible, nor necessary to maintain it at a specific level. The oxidizers are mostly O2, and the reducers are made up of mostly organics, ie: food, waste, additives we put in the tank, and the organisms themselves, all are under attack from oxidizers.
From our point of view keeping the redox levels between 200-500mV is acceptable, with 300-450mV being preferable.
The part of the article that interested me the most was the discussion of ORP and water quality. It is suggested that a higher ORP does not mean better water quality. And that by adding oxidizers, such as O3, you may be only masking a problem, not fixing it. The example given is that organics in the water column will turn the water yellow. By introducing O3 these organics are not removed merely the color changes from yellow to clear.
Now this may be good for light penetration into the tank, but what does stripping the color from the organics have on the tank. It could not be said if it was a good thing or bad thing. So even if you use O3 the advice of our own Jackson6745 seems proper, get a bigger skimmer!
Randy states, "If an oxidizer is added and ORP goes up in 30 seconds, is the water purer? Not likely. More likely, that addition shifted many of the redox species to their more oxidizing forms. Is that beneficial? Maybe. Is it detrimental? Maybe. For example, the bioavailability of certain metals may depend on the form that those metals take. Is increasing bioavailability of them desirable? It all depends on the details. Details that are simply not known for aquaria.
Perhaps continual use of ozone does help clear some organics from the water, and there is a long term benefit that may or may not be related to actual ORP readings that one gets from an aquarium. Is there data showing that to be the case, and then coupling that with some objective measure of benefit to the aquarium? Does that outweigh the potential concerns about the toxicity of reactive oxidants in aquaria? Again, I do not know the answer. Only careful studies with clear endpoints can give such an answer."
Even if you don't plan on using ozone to maintain your tank reading about ORP is valuable. There is even a way to measure the ORP of your sandbed if you have one, this can alert you to an impending problem if done on a regular schedule.
For myself I'm going to do more research on the subject. I still plan on using ozone, but this article has helped my knowledge of what is happening in my reef tanks water.
This is a misunderstood and difficult subject to understand as it relates to our aquariums.
While doing research for the effects of ozone I found this article that Randy Holmes-Farley wrote, ORP and the Reef Aquarium.
I suggest that you read it as it raises some questions about aquarium water quality and the things we do to control it.
One thing said is that keeping track of ORP is not always necessary, unless you are using O3. It's more about ORP and the use of O3 I would like to focus on, but any insights you have on ORP would be valuable to hear.
A brief summery of ORP: it represents the balance between chemical oxidizers who want to gather electrons, and chemical reducers who want to get rid of their electrons. This balance is always changing, and is effected by so many different variables it is impossible, nor necessary to maintain it at a specific level. The oxidizers are mostly O2, and the reducers are made up of mostly organics, ie: food, waste, additives we put in the tank, and the organisms themselves, all are under attack from oxidizers.
From our point of view keeping the redox levels between 200-500mV is acceptable, with 300-450mV being preferable.
The part of the article that interested me the most was the discussion of ORP and water quality. It is suggested that a higher ORP does not mean better water quality. And that by adding oxidizers, such as O3, you may be only masking a problem, not fixing it. The example given is that organics in the water column will turn the water yellow. By introducing O3 these organics are not removed merely the color changes from yellow to clear.
Now this may be good for light penetration into the tank, but what does stripping the color from the organics have on the tank. It could not be said if it was a good thing or bad thing. So even if you use O3 the advice of our own Jackson6745 seems proper, get a bigger skimmer!
Randy states, "If an oxidizer is added and ORP goes up in 30 seconds, is the water purer? Not likely. More likely, that addition shifted many of the redox species to their more oxidizing forms. Is that beneficial? Maybe. Is it detrimental? Maybe. For example, the bioavailability of certain metals may depend on the form that those metals take. Is increasing bioavailability of them desirable? It all depends on the details. Details that are simply not known for aquaria.
Perhaps continual use of ozone does help clear some organics from the water, and there is a long term benefit that may or may not be related to actual ORP readings that one gets from an aquarium. Is there data showing that to be the case, and then coupling that with some objective measure of benefit to the aquarium? Does that outweigh the potential concerns about the toxicity of reactive oxidants in aquaria? Again, I do not know the answer. Only careful studies with clear endpoints can give such an answer."
Even if you don't plan on using ozone to maintain your tank reading about ORP is valuable. There is even a way to measure the ORP of your sandbed if you have one, this can alert you to an impending problem if done on a regular schedule.
For myself I'm going to do more research on the subject. I still plan on using ozone, but this article has helped my knowledge of what is happening in my reef tanks water.
