Salinity and ORP relation?

[kilnakorr]

Yep - at least in the currents that can be actual in the aquarium hobby. Do a googling for electrofishing in saltwater. There is methods that works in saltwater too but the currents in use is very high - not likely in an aquarium.

However - do not be sad if you had the wrong impression before - you are not the only one that have thought that it will harm the fish. see here - In that thread I had to do a 180 degree turn in the same discussion - but 6 years ago As you say - Jeg måtte lægge mig fladt ned in this matter

Sincerely Lasse

Makes sense.
Think I'll go get a new voltmeter and see if whats going on in the tank - before and after the jump in mV.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, ORP should not change just because of a salinity change except as that change alters other real properties, such as pH, that themselves can impact ORP.

 

[kilnakorr]

FWIW, ORP should not change just because of a salinity change except as that change alters other real properties, such as pH, that themselves can impact ORP.

This was the very point of the thread.
There must be something else going on in my tank, or simply a faulty probe.
Using ground on plugs/equipment is not very common here, and seems I don't have a single wire with ground anywhere, so can't test for stray voltage in the tank right now

 

[Randy Holmes-Farley Verified Community Expert]

This was the very point of the thread.
There must be something else going on in my tank, or simply a faulty probe.
Using ground on plugs/equipment is not very common here, and seems I don't have a single wire with ground anywhere, so can't test for stray voltage in the tank right now

I added the info that salinity is not impacting ORP directly. Some folks suggested it might. I do not think grounding impacts it either. ORP is not a current flow technique.

I am unclear on the data you are generating. In one post you are talking about removing the conductivity probe from the water, and still show a reading. No idea what that has to do with conductivity in the water impacting ORP. Perhaps that is not what you meant to suggest.

This all sounds like a device measurement problem to me, not any sort of real ORP effect.

ORP does need both a redox electrode and a reference electrode (different than a ground probe) to be in the same water. I’m not sure where your device puts its reference electrode. Is it a normal ORP probe?

 

[kilnakorr]

I am unclear on the data you are generating. In one post you are talking about removing the conductivity probe from the water, and still show a reading. No idea what that has to do with conductivity in the water impacting ORP. Perhaps that is not what you meant to suggest.

Removing the conductivity probe was just to see what would happen, as the ORP reading changes when conductivity changes, which it shouldn't.

This all sounds like a device measurement problem to me, not any sort of real ORP effect.

I'm pretty sure the readings are not correct, and surely a device or interference issue.

Is it a normal ORP probe?

I believe so, without knowing what a 'normal' ORP probe means.

 

[Randy Holmes-Farley Verified Community Expert]

Removing the conductivity probe was just to see what would happen, as the ORP reading changes when conductivity changes, which it shouldn't.

I'm pretty sure the readings are not correct, and surely a device or interference issue.

I believe so, without knowing what a 'normal' ORP probe means.

A normal ORP probe has a built in reference electrode, while some havw separate redox electrodes to be used with a reference electrode on a different probe.

ORP

Knowledge about ORP

aperainst.com

Anatomy of an ORP sensor

ORP sensors work by measuring the electrical potential (voltage) between two electrodes in contact with water. Both electrodes are often contained in a single unit called a combination electrode. One electrode is called the indicator electrode, and it is usually made of platinum (other materials such as gold or graphite are also sometimes used).

The other electrode is called the reference electrode. The reference electrode is usually made of silver and silver chloride (Ag/AgCl electrodes), although electrodes made of mercury and mercury chloride (called “calomel electrodes”) are sometimes used. This electrode contains a filling solution containing potassium chloride.

Electrons from the water interact with both electrodes, creating a voltage between them that is read by the meter.

 

[Randy Holmes-Farley Verified Community Expert]

Instead of removing the conductivity probe, one suggestion is to see the effect of taking the ORP probe from the tank into a cup of tank water isolated from the tank and see what that shows. True ORP will be unchanged. If the ORP does change, the device is being messed with by other aspects of the water.

 

[kilnakorr]

Instead of removing the conductivity probe, one suggestion is to see the effect of taking the ORP probe from the tank into a cup of tank water isolated from the tank and see what that shows. True ORP will be unchanged. If the ORP does change, the device is being messed with by other aspects of the water.

I actually just did this.
ORP rises about 100 'points' / mV, when testing the water outside the tank.
Also, changes in conductivity does not have any impact on the ORP readings.

 

[Lasse]

Its a standard dubble junction ORP probe if it is GHL:s own you use. It has the reference inside. How long time have the redox probe been in your water? IME - it takes around 1/2 to one month before these electrodes is adapted to your water and give a stable reading in oxygen rich water. In anaerobic environment - they adapt with a stable reading in some days IME. - reason unknown.

Sincerely Lasse

 

[kilnakorr]

Its a standard dubble junction ORP probe if it is GHL:s own you use. It has the reference inside. How long time have the redox probe been in your water? IME - it takes around 1/2 to one month before these electrodes is adapted to your water and give a stable reading in oxygen rich water. In anaerobic environment - they adapt with a stable reading in some days IME. - reason unknown.

Sincerely Lasse

Well, even if the probe is a bit unstable I wouldn't expect it to change readings based on other probes.
As already tested, this only happens in the sump, and not when measuring outside the tank in a cup af tank water.

 

[kilnakorr]

Just to update. It seems my UV is causing this.
Bothe the wierd jumps in ORP readings in general, but also the drop when conductivity probe is removed.
Seems to add roughly 20v, when testing the tank with a voltmeter.

 

[gbroadbridge]

Just to update. It seems my UV is causing this.
Bothe the wierd jumps in ORP readings in general, but also the drop when conductivity probe is removed.
Seems to add roughly 20v, when testing the tank with a voltmeter.

Have you checked that there is no water or moisture leakage into the bulb containment area (quartz tube)?

 

[kilnakorr]

Have you checked that there is no water or moisture leakage into the bulb containment area (quartz tube)?

No. I just found out a few minutes ago.
I change the 'ballast' a few weeks ago, so it could be either the new ballast or a small leak/moisture in the tube as you say.
I do know there is no ground wire though in the unit.
I've turned it off for now, until I have the time to check it out.

 

[Randy Holmes-Farley Verified Community Expert]

No. I just found out a few minutes ago.
I change the 'ballast' a few weeks ago, so it could be either the new ballast or a small leak/moisture in the tube as you say.
I do know there is no ground wire though in the unit.
I've turned it off for now, until I have the time to check it out.

Some electrical devices, such as the Pinpoint pH meter, are (or at least were) known to have electrical interference from some ballasts for lights. It's a through air effect of the electric field, possibly to the cord acting as an antennae, not through the water. In that case, putting the meter on a battery solves it.

 

[kilnakorr]

Some electrical devices, such as the Pinpoint pH meter, are (or at least were) known to have electrical interference from some ballasts for lights. It's a through air effect of the electric field, possibly to the cord acting as an antennae, not through the water. In that case, putting the meter on a battery solves it.

Thanks for the info.
This is a new thing happening, so most likely the new ballast in the UV unit.
I will check this out when I have time.
The redox probe is not important as I do not run ozone at the moment. I was curious about the wierd readings, and conductivity relation.
Glad I've found the cause and shut down the uv unit.