ORP probe

Shawn_epicurious · Jul 20, 2020

Oxidation Reduction Potential... ORP. I’ve read about it. I don’t really get it. Really... very few people seem to get what it actually is... so, I am looking for a simple explanation... not about what it is... but why APEX thinks I need to measure it.

It seems to me that what APEX did, was come up with a probe, that needs no calibration and is very very accurate at measuring... something. And then tried to invent a reason for me to to track it. They seem to want me to measure and control ....ozone? My tank has never dropped outside of what they consider to be a “normal range”

What am I missing?

Aussiemarine · Jul 20, 2020

Hmm I’m in the same boat. I have read up and don’t fully understand it BUT what I do know is that it can be a good indicator if something goes wrong or happens within the tank.

for example when I noticed the tank went super cloudy (turns out it was a snail spawning event) the ORP dropped drastically by almost 100- once it was over it sharply increased back to normal levels. I assume this would happen if say something large died or if a Nem got stuck in the power head. So looking at the apex remotely I can see if something’s gone wrong with the water quality by a sharp decline in ORP.

What its actually intended for on my apex I don’t know

JSully_94 · Jul 20, 2020

I found this on the web. Although it concerns large bodies of water, I have a feeling the same processes are similar in our replicated aquatic environments.

The source specifically states, “When ORP is low, dissolved oxygen is low, toxicity of certain metals and contaminants can increase, and there is lots of dead and decaying material in the water that cannot be cleared or decomposed.”

So basically low ORP means less capacity to break down harmful substances. At least that’s my understanding.

https://www.enr.gov.nt.ca/sites/enr/files/oxidation-reduction_potential.pdf

X-37B · Jul 20, 2020

In simple reef terms its a measurement of how clean the water is and its ability to break down contaminants.

Shawn_epicurious · Jul 20, 2020

JSully_94 said:
I found this on the web. Although it concerns large bodies of water, I have a feeling the same processes are similar in our replicated aquatic environments.

The source specifically states, “When ORP is low, dissolved oxygen is low, toxicity of certain metals and contaminants can increase, and there is lots of dead and decaying material in the water that cannot be cleared or decomposed.”

So basically low ORP means less capacity to break down harmful substances. At least that’s my understanding.

https://www.enr.gov.nt.ca/sites/enr/files/oxidation-reduction_potential.pdf

I like that : )

Shawn_epicurious · Jul 20, 2020

90's reefer said:
In simple reef terms its a measurement of how clean the water is and its ability to break down contaminants.

I thought the word “Oxidation“ had to do with oxygen breaking down metals... you know, like rust.

Rick.45cal · Jul 20, 2020

It’s a measurement of whether oxydation reactions are more likely to occur or whether reduction reactions are more likely to occur.

It’s arguable whether it’s worth paying attention to or not. It’s useful if you are using ozone to make sure you don’t overdo it. That’s a whole other argument as to whether ozone is worth dabbling in.

Shawn_epicurious · Jul 20, 2020

Rick.45cal said:
It’s a measurement of whether oxydation reactions are more likely to occur or whether reduction reactions are more likely to occur.

It’s arguable whether it’s worth paying attention to or not. It’s useful if you are using ozone to make sure you don’t overdo it. That’s a whole other argument as to whether ozone is worth dabbling in.

That part I got, but to be honest, it felt more like inventing a new reason to sell me a gadget. (I am a gadget guy!)

Rick.45cal · Jul 20, 2020

Shawn_epicurious said:
That part I got, but to be honest, it felt more like inventing a new reason to sell me a gadget. (I am a gadget guy!)

They didn’t invent it, ORP and REDOX probes have been around a lot longer than Apex, though that doesn’t mean they don’t want to sell it to you!

X-37B · Jul 20, 2020

Yea more gadgets.
I measured it when running ozone in the 80's.
Oxidation is when a chemical loses electrons.
Reduction is when a chemical gains electrons.
Had to look that one up to make sure I remembered correctly lol.

Shawn_epicurious · Jul 20, 2020

90's reefer said:
Yea more gadgets.
I measured it when running ozone in the 80's.
Oxidation is when a chemical loses electrons.
Reduction is when a chemical gains electrons.
Had to look that one up to make sure I remembered correctly lol.

Better definition than mine : )

GravaD Reefing · Jul 20, 2020

I would honestly look at it as a cheaper way to monitor dissolved oxygen. Just keep in mind that it isn’t a direct measurement. But generally anything over 100 should be safe. But readings will vary based on nutrients/substances in the water. Above 100 there is high oxygen availability and the system will promote nitrification.

Just below this, the system (probe location) becomes anoxic and is more likely to reduce substances. In some cases this is good as it allows for denitrification NO3>N2 gas. if kept in this state too long, eventually all the oxygen will be removed from molecules and the system will become septic. As a whole you will want to avoid this but there is some benefit to having anoxic zones in that tank to help reduce nitrate, however these are typically deep in the rock where the probe can’t reach.

Randy Holmes-Farley · Jul 21, 2020

I discuss in great detail what ORP is and what use it is (or is not), in this article:

ORP and the Reef Aquarium - Reefkeeping.com

http://reefkeeping.com/issues/2003-12/rhf/feature/index.htm

Randy Holmes-Farley · Jul 21, 2020

Shawn_epicurious said:
I thought the word “Oxidation“ had to do with oxygen breaking down metals... you know, like rust.

That is an oxidation reaction, but there are many others that do not involve metals or oxygen.

Not all oxidation reactions impact ORP.

Shawn_epicurious · Jul 21, 2020

Randy Holmes-Farley said:
I discuss in great detail what ORP is and what use it is (or is not), in this article:

ORP and the Reef Aquarium - Reefkeeping.com

http://reefkeeping.com/issues/2003-12/rhf/feature/index.htm

You rock Randy! Thank you for this : )

Randy Holmes-Farley · Jul 21, 2020

Shawn_epicurious said:
You rock Randy! Thank you for this : )

You're welcome.

Happy Reefing.

Shawn_epicurious · Jul 28, 2020

ORP appears to maintain itself quite nicely with water changes. The graph below shows my last water change on June 22nd. ....seems to make an arguement for frequent water changes. : ) I recently changed from weekly 10% to 15% every two weeks.

Randy Holmes-Farley · Jul 29, 2020

I don't consider a higher ORP necessarily desirable, but I'm curious in your graphs exactly where water changes took place.

Many folks note that their water changes drop their ORP due to low ORP chemicals in a salt mix.

Shawn_epicurious · Jul 29, 2020

Randy Holmes-Farley said:
I don't consider a higher ORP necessarily desirable, but I'm curious in your graphs exactly where water changes took place.

Many folks note that their water changes drop their ORP due to low ORP chemicals in a salt mix.

I had to look at a calendar to be sure. I did a water change on the day before this graph starts, on the 21st. You know I am not a chemist : ) but... I’ll do a few more graphs over time to see how a water change moves the number : )

Randy Holmes-Farley · Jul 29, 2020

Shawn_epicurious said:
I had to look at a calendar to be sure. I did a water change on the day before this graph starts, on the 21st. You know I am not a chemist : ) but... I’ll do a few more graphs over time to see how a water change moves the number : )

Great. In the meantime, here's an article of mine on ORP:

ORP and the Reef Aquarium - Reefkeeping.com