Salinity and ORP relation?

[kilnakorr]

I just calibrated my handheld conductivity probe and wondered if same solution could be used with my GHL probe.
I noticed that as the salinity changes when moving the probe, rinsing it etc. the ORP readings were crazy.
ORP seems to rise along with the salinity.
Does this make sense, or should salinity readings not have any influence on ORP readings?

 

[Lasse]

I just calibrated my handheld conductivity probe and wondered if same solution could be used with my GHL probe.

Which GHL probe or GHL redox probe. ORP is given from a redox probe and it is ± mV A GHL salinity probe give the answer in mS - the same as you handhold

Sincerely Lasse

 

[kilnakorr]

Which GHL probe or GHL redox probe. ORP is given from a redox probe and it is ± mV A GHL salinity probe give the answer in mS - the same as you handhold

Sincerely Lasse

Sorry, I might have added unnecessary info.
I am wondering why the ORP reading drops, when salinity readings drop.
If I leave my redox probe in the same, but remove my salinity probe, the ORP reading goes crazy:

First two are normal readings, with both probes in the sump.
Next two, are with salinity/conductivity probe out of water.

 

[Lasse]

Never seen that. ORP use to react to pH in opposite maner - but never seen it react to different conductivity readings. In the second case - if conductivity probe is out from water and in air - it should read zero or close to zero.

Sincerely Lasse

 

[kilnakorr]

Never seen that. ORP use to react to pH in opposite maner - but never seen it react to different conductivity readings. In the second case - if conductivity probe is out from water and in air - it should read zero or close to zero.

Sincerely Lasse

Yes. It does react to ph in opposite manner, but have no clue why it also reacts to conductivity. I couldn't come with any logical reason, but could be a bug in the GHL software or something.
Btw. The readings where just a few quick pictures, as I removed the probe.
It even has a negative redox reading, as conductivity gets lower:

 

[gbroadbridge]

I'm not 100% certain, but sometimes an ORP probe uses the conductivity probe as a ground reference.

 

[kilnakorr]

I'm not 100% certain, but sometimes an ORP probe uses the conductivity probe as a ground reference.

If that is true, then it would make a lot of sense.
I wonder what would happen if I disabled the conductivity probe.

 

[gbroadbridge]

If that is true, then it would make a lot of sense.
I wonder what would happen if I disabled the conductivity probe.

Disabled in software will still leave the ground intact.

You could unplug the Conductivity probe, and then just use a length of hookup wire from the outside of the BNC connector into the sump. That would give an earth reference to the Profilux.

I'm interested, let me know

I was just recalibrating my ORP probe yesterday for an ozone generator that arrives on Monday, it'll be interesting if lack of ground could cause a problem.

 

[kilnakorr]

Disabled in software will still leave the ground intact.

You could unplug the Conductivity probe, and then just use a length of hookup wire from the outside of the BNC connector into the sump. That would give an earth reference to the Profilux.

I'm interested, let me know

I was just recalibrating my ORP probe yesterday for an ozone generator that arrives on Monday, it'll be interesting if lack of ground could cause a problem.

Well, unplugging might be the best test.
I would not think the profilux requires a conductivity probe in order to measure redox.

 

[Lasse]

I'm not 100% certain, but sometimes an ORP probe uses the conductivity probe as a ground reference.

Never heard about that - at least not with GHL products.

I would not think the profilux requires a conductivity probe in order to measure redox

Nope - I have used ORP probes without conductivity probes for many years - even in systems without ability to measure conductivity at all.

I would open a ticket with GHL - do it here Use guest login

Sincerely Lasse

 

[gbroadbridge]

Never heard about that - at least not with GHL products.


Nope - I have used ORP probes without conductivity probes for many years - even in systems without ability to measure conductivity at all.

I would open a ticket with GHL - do it here Use guest login

Sincerely Lasse

ORP measures very tiny voltages across the probe, so it will depend on the electrical characteristics of the tank, .i.e. does the tank have a ground probe, etc.

I'll run some tests here just for fun

 

[kilnakorr]

ORP measures very tiny voltages across the probe, so it will depend on the electrical characteristics of the tank, .i.e. does the tank have a ground probe, etc.

I'll run some tests here just for fun

I might.
Could also just be a faulty probe, reacting to some power noise.

 

[Lasse]

ORP measures very tiny voltages across the probe, so it will depend on the electrical characteristics of the tank, .i.e. does the tank have a ground probe, etc.

I doubt - the important issue is what surround the wires, if it is PSU in close distance to the tiny wire from the probes or not, if any magnetically fields is created by high currents in surrounding wires and so on . Can you explain how a GHL conductivity probe can act as a ground probe for me?

Hint - From GHL website

All sensors are galvanically isolated and can therefore easily be used in parallel in any combination.

Further on - Most tanks with a aquarium computers have titan heaters - at least here in Sweden. A titan heater must be grounded, hence it serve as a ground probe. But it is true - it is always important to ground a saltwater aquarium especially for personal protection.

Sincerely Lasse

 

[gbroadbridge]

I doubt - the important issue is what surround the wires, if it is PSU in close distance to the tiny wire from the probes or not, if any magnetically fields is created by high currents in surrounding wires and so on . Can you explain how a GHL conductivity probe can act as a ground probe for me?

I agree that the OP's strange ORP reading is probably related to EMI from other equipment. Especially given the proliferation of noisy PSU's from China.

I did a test here, and disconnecting the conductivity probe did not materially affect the ORP reading.

I assumed that the BNC connectors shared a common ground, but that was incorrect and they are in fact electrically isolated from each other so the conductivity probe cannot provide a electrical ground for the ORP probe.

From GHL website


Further on - Most tanks with a aquarium computers have titan heaters - at least here in Sweden. A titan heater must be grounded, hence it serve as a ground probe. But it is true - it is always important to ground a saltwater aquarium especially for personal protection.

Sincerely Lasse

Well yes, but it is not common here in Australia especially since most housholds use RCD protection rather than GFCI meaning a ground is not necessary for current imbalance to be detected.

Graham

 

[kilnakorr]

I doubt - the important issue is what surround the wires, if it is PSU in close distance to the tiny wire from the probes or not, if any magnetically fields is created by high currents in surrounding wires and so on . Can you explain how a GHL conductivity probe can act as a ground probe for me?

Hint - From GHL website


Further on - Most tanks with a aquarium computers have titan heaters - at least here in Sweden. A titan heater must be grounded, hence it serve as a ground probe. But it is true - it is always important to ground a saltwater aquarium especially for personal protection.

Sincerely Lasse

The probe wires could be damaged somewhere.
I'm not running a ground probe or titanium heater, so maybe I should get one.
Have to check if the entire powerline runs with ground wire otherwise it won't matter.

Also, the readings does look a bit wierd lately, as it jumps about 100 mV around midnight and back down at 10.00 (10 am):

 

[Lasse]

Well yes, but it is not common here in Australia especially since most housholds use RCD protection rather than GFCI meaning a ground is not necessary for current imbalance to be detected.

Yes it is here too. It must be installed in new installations - no matter what. But the old GFCI is still with for personal safety. IMO - it is more important to use grounding in a saltwater aquarium if you only run RCD protection. If you do - it will work directly you get a leak current to ground, if you do not have it - it will not detect any leak currents before you put your hand into the water...........

However - i would never use ground protection in freshwater or water below 10 ppt salt. This is because it will create a electrical field (read current) in the water that will pass through living things if they are "salter" than the water. If the water have higher conductivity than the fish - the current will not go through the fish and is harmless for the fish. In fresh water RCD is enough in order to create a safe environment. this is especial harmfull if the equipment use AC.

Sincerely Lasse

 

[Lasse]

Also, the readings does look a bit wierd lately, as it jumps about 100 mV around midnight and back down at 10.00 (10 am):

Is there anything else that happens at 00:00 and 10:00?. Light on/off - refugium light on/off or something else like adding of additives?

sincerely Lasse

 

[kilnakorr]

Yes it is here too. It must be installed in new installations - no matter what. But the old GFCI is still with for personal safety. IMO - it is more important to use grounding in a saltwater aquarium if you only run RCD protection. If you do - it will work directly you get a leak current to ground, if you do not have it - it will not detect any leak currents before you put your hand into the water.

However - i would never use ground protection in freshwater or water below 10 ppt salt. This is because it will create a electrical field (read current) in the water that will pass through living things if they are "salter" than the water. If the water have higher conductivity than the fish - the current will not go through the fish and is harmless for the fish. In fresh water RCD is enough in order to create a safe environment.

Sincerely Lasse

So all this discussion about ground probes can be dangerous for the inhabitants as it completes any stray voltage, is only true in freshwater tanks and has no concern in saltwater?

 

[kilnakorr]

Is there anything else that happens at 00:00 and 10:00. Light on/off - refugium light on/off or something else like adding of additives?

sincerely Lasse

Well, lights does come on at 10.00, but are shuts off before 00.00.

I might need to look at the whole setup.
I could simply turn light off for a few, and check the live readings.

 

[Lasse]

So all this discussion about ground probes can be dangerous for the inhabitants as it completes any stray voltage, is only true in freshwater tanks and has no concern in saltwater?

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