Salinity Probe Readings

[Tastee]

I have two Apex controlled tanks and don’t have any issues with the conductivity probes. They are a bit fiddly to calibrate and bed in but once that’s done they seem quite stable. I found I needed to adjust the temp calibration over a few weeks to stop fluctuations due to temp and then recalibrate the probe, but after that it’s been fine. Bubbles are an issue so you do need to be careful with that during calibration and when in the tank. Occasionally (once a year or less) it starts reporting a major change in salinity, but a clean and careful shake fixed that for me. For some reason the last time it did that I had to recalibrate it, but after that all good. I do recommend keeping a calibration sachet on hand - I carefully reclose and keep reusing mine as needed, feel they are good for a year or so if you are careful.

 

[Bramzor]

Apex Salinity probes are a pain to calibrate. For the following reasons:

1. Do NOT calibrate if your calibration is already correct. So instead of blindly doing a calibration, first put the probe in the calibration fluid and measure the salinity. If this shows 35 (when temperature is the same as in the tank), THERE IS NO REASON TO CALIBRATE! If its in a range of 34.8-35.2, there is also NO POINT in trying to calibrate it.
2. Most of the time people try to calibrate the using automated calibration option which gives you 0 visibility during the calibration. You should use the manual option instead.
3. Apex calibration is buggy. I noticed when trying to calibrate multiple times in a row it just shows wrong values during calibration, for example a 0 reading for a dry probe. I noticed when resetting the Apex by pulling out the power, it stopped showing that 0 reading. So if you have a reading of 48 salinity or something like that, you might just have calibrated your probe with a 0 reading for a dry probe which is a faulty reading. Should be something in the range of (60-75) for a dry probe and about 538-545 for a probe in calibration fluid of 35 salinity (53.000 mS).
4. A probe measures milivolts mV s which is a tiny measurement and also tiny fluctuations. If you put the probe cable next to ANY other cable, it might return different values. One of the things that you could do it making sure the cable of the salinity probe NEVER goes anywhere near another cable, not even close to the Apex itself. You could also calibrate when lights and gear is off. This should also allow you to calibrate with less interference of other equipment.
5. Air inside the probe causes bad readings. Always turn the probe upside down in the fluid to make sure you do not have any bubbles in it (so turn it upside down in the sump). Obviously you cannot do this in the calibration fluid, but you might cut a corner of the calibration fluid bag, but in the probe, push out as much air as possible and take some tape and tape it off. This will allow you to hold the probe upside down so there will never be any bubbles in it. If you have some experience doing good calibration, it might already be enough to hold the probe at an angle, with the hole up and tap it a few times so air bubbles would go out.
6. ALWAYS LET IT SETTLE FOR AT LEAST 5 MINUTES, except if you know the value you are trying to reach and hit it the first time, but even than it wouldn't hurt to leave it for 5 minutes.

So if you make sure the above 5 points are covered, it will increase the possibility of doing a good calibration.

How to calibrate? As already mentioned, use manual method. Make sure temperature of the calibration fluid and the tank are the same. Make sure it is dry and read the appropriate value (as I mentioned, somewhere between 60-75). Press next, pick the right calibration fluid from the list. Put it in the bag and press next. It should show a value between 538-545. Open up a session of your Apex (but using the local IP address, not the app or apex hostname), so you have a direct connection with the Apex open. That interface is GREY and not the WHITE interface you normally have. You will see the current salinity value based on the current measurement (calibration measurement) and based on the OLD calibration values. This can help you during the calibration.

For example:
I had a bad calibration with a dry probe reading value of 0. Which shows a salinity of 48 when measuring the salinity in my tank. So during the next calibration it would show a value of 35.8 for a settling value of 542. That is because the last calibration was way off, so that is not an issue. Personally I'm looking for a settling value of 542-540 anyway.
When you press save and you had a bad calibration before and if you are a bit lucky, you might see a jump in salinity value. So after calibration (pressing the last Next), I noticed salinity in the second screen (on the Apex directly via the local IP address) a salinity of 31.9, which a few seconds after jumps towards 34.9. What does this mean?
This means that using my bad calibration, the calibration fluid measured a salinity of 35.8 during the calibration (which uses settling numbers from apex itself), although the measurement that was hidden was in fact 31.9 for the calibration fluid (so way off) and a second after when calculation was done using the new settling values, it was changed to 34.9 which is good enough for a calibration fluid of 35.


So what makes it so hard? Lot of things and most likely the combination of all of them.

 

[Amado]

Apex Salinity probes are a pain to calibrate. For the following reasons:

1. Do NOT calibrate if your calibration is already correct. So instead of blindly doing a calibration, first put the probe in the calibration fluid and measure the salinity. If this shows 35 (when temperature is the same as in the tank), THERE IS NO REASON TO CALIBRATE! If its in a range of 34.8-35.2, there is also NO POINT in trying to calibrate it.
2. Most of the time people try to calibrate the using automated calibration option which gives you 0 visibility during the calibration. You should use the manual option instead.
3. Apex calibration is buggy. I noticed when trying to calibrate multiple times in a row it just shows wrong values during calibration, for example a 0 reading for a dry probe. I noticed when resetting the Apex by pulling out the power, it stopped showing that 0 reading. So if you have a reading of 48 salinity or something like that, you might just have calibrated your probe with a 0 reading for a dry probe which is a faulty reading. Should be something in the range of (60-75) for a dry probe and about 538-545 for a probe in calibration fluid of 35 salinity (53.000 mS).
4. A probe measures milivolts mV s which is a tiny measurement and also tiny fluctuations. If you put the probe cable next to ANY other cable, it might return different values. One of the things that you could do it making sure the cable of the salinity probe NEVER goes anywhere near another cable, not even close to the Apex itself. You could also calibrate when lights and gear is off. This should also allow you to calibrate with less interference of other equipment.
5. Air inside the probe causes bad readings. Always turn the probe upside down in the fluid to make sure you do not have any bubbles in it (so turn it upside down in the sump). Obviously you cannot do this in the calibration fluid, but you might cut a corner of the calibration fluid bag, but in the probe, push out as much air as possible and take some tape and tape it off. This will allow you to hold the probe upside down so there will never be any bubbles in it. If you have some experience doing good calibration, it might already be enough to hold the probe at an angle, with the hole up and tap it a few times so air bubbles would go out.
6. ALWAYS LET IT SETTLE FOR AT LEAST 5 MINUTES, except if you know the value you are trying to reach and hit it the first time, but even than it wouldn't hurt to leave it for 5 minutes.

So if you make sure the above 5 points are covered, it will increase the possibility of doing a good calibration.

How to calibrate? As already mentioned, use manual method. Make sure temperature of the calibration fluid and the tank are the same. Make sure it is dry and read the appropriate value (as I mentioned, somewhere between 60-75). Press next, pick the right calibration fluid from the list. Put it in the bag and press next. It should show a value between 538-545. Open up a session of your Apex (but using the local IP address, not the app or apex hostname), so you have a direct connection with the Apex open. That interface is GREY and not the WHITE interface you normally have. You will see the current salinity value based on the current measurement (calibration measurement) and based on the OLD calibration values. This can help you during the calibration.

For example:
I had a bad calibration with a dry probe reading value of 0. Which shows a salinity of 48 when measuring the salinity in my tank. So during the next calibration it would show a value of 35.8 for a settling value of 542. That is because the last calibration was way off, so that is not an issue. Personally I'm looking for a settling value of 542-540 anyway.
When you press save and you had a bad calibration before and if you are a bit lucky, you might see a jump in salinity value. So after calibration (pressing the last Next), I noticed salinity in the second screen (on the Apex directly via the local IP address) a salinity of 31.9, which a few seconds after jumps towards 34.9. What does this mean?
This means that using my bad calibration, the calibration fluid measured a salinity of 35.8 during the calibration (which uses settling numbers from apex itself), although the measurement that was hidden was in fact 31.9 for the calibration fluid (so way off) and a second after when calculation was done using the new settling values, it was changed to 34.9 which is good enough for a calibration fluid of 35.


So what makes it so hard? Lot of things and most likely the combination of all of them.

My solution is use a $29 refractor meter from amazon.
Calibration instructions for refractometer.
Step1 drip calibration fluid in the lens.
Step 2 look and see what’s the salinity.
step 3 35 or 1.026 your done

 

[Bramzor]

My solution is use a $29 refractor meter from amazon.
Calibration instructions for refractometer.
Step1 drip calibration fluid in the lens.
Step 2 look and see what’s the salinity.
step 3 35 or 1.026 your done

You could also lick the water to measure salinity.... You cannot compare a refractometer with any type of probe. Probe is 10x as accurate if calibrated properly and if you want to measure swings in salinity you need a probe anyway.

 

[Amado]

Apex Salinity probes are a pain to calibrate. For the following reasons:

1. Do NOT calibrate if your calibration is already correct. So instead of blindly doing a calibration, first put the probe in the calibration fluid and measure the salinity. If this shows 35 (when temperature is the same as in the tank), THERE IS NO REASON TO CALIBRATE! If its in a range of 34.8-35.2, there is also NO POINT in trying to calibrate it.
2. Most of the time people try to calibrate the using automated calibration option which gives you 0 visibility during the calibration. You should use the manual option instead.
3. Apex calibration is buggy. I noticed when trying to calibrate multiple times in a row it just shows wrong values during calibration, for example a 0 reading for a dry probe. I noticed when resetting the Apex by pulling out the power, it stopped showing that 0 reading. So if you have a reading of 48 salinity or something like that, you might just have calibrated your probe with a 0 reading for a dry probe which is a faulty reading. Should be something in the range of (60-75) for a dry probe and about 538-545 for a probe in calibration fluid of 35 salinity (53.000 mS).
4. A probe measures milivolts mV s which is a tiny measurement and also tiny fluctuations. If you put the probe cable next to ANY other cable, it might return different values. One of the things that you could do it making sure the cable of the salinity probe NEVER goes anywhere near another cable, not even close to the Apex itself. You could also calibrate when lights and gear is off. This should also allow you to calibrate with less interference of other equipment.
5. Air inside the probe causes bad readings. Always turn the probe upside down in the fluid to make sure you do not have any bubbles in it (so turn it upside down in the sump). Obviously you cannot do this in the calibration fluid, but you might cut a corner of the calibration fluid bag, but in the probe, push out as much air as possible and take some tape and tape it off. This will allow you to hold the probe upside down so there will never be any bubbles in it. If you have some experience doing good calibration, it might already be enough to hold the probe at an angle, with the hole up and tap it a few times so air bubbles would go out.
6. ALWAYS LET IT SETTLE FOR AT LEAST 5 MINUTES, except if you know the value you are trying to reach and hit it the first time, but even than it wouldn't hurt to leave it for 5 minutes.

So if you make sure the above 5 points are covered, it will increase the possibility of doing a good calibration.

How to calibrate? As already mentioned, use manual method. Make sure temperature of the calibration fluid and the tank are the same. Make sure it is dry and read the appropriate value (as I mentioned, somewhere between 60-75). Press next, pick the right calibration fluid from the list. Put it in the bag and press next. It should show a value between 538-545. Open up a session of your Apex (but using the local IP address, not the app or apex hostname), so you have a direct connection with the Apex open. That interface is GREY and not the WHITE interface you normally have. You will see the current salinity value based on the current measurement (calibration measurement) and based on the OLD calibration values. This can help you during the calibration.

For example:
I had a bad calibration with a dry probe reading value of 0. Which shows a salinity of 48 when measuring the salinity in my tank. So during the next calibration it would show a value of 35.8 for a settling value of 542. That is because the last calibration was way off, so that is not an issue. Personally I'm looking for a settling value of 542-540 anyway.
When you press save and you had a bad calibration before and if you are a bit lucky, you might see a jump in salinity value. So after calibration (pressing the last Next), I noticed salinity in the second screen (on the Apex directly via the local IP address) a salinity of 31.9, which a few seconds after jumps towards 34.9. What does this mean?
This means that using my bad calibration, the calibration fluid measured a salinity of 35.8 during the calibration (which uses settling numbers from apex itself), although the measurement that was hidden was in fact 31.9 for the calibration fluid (so way off) and a second after when calculation was done using the new settling values, it was changed to 34.9 which is good enough for a calibration fluid of 35.


So what makes it so hard? Lot of things and most likely the combination of all of them.

by the way all jokes aside this is the best explanation on how to calibrate the salinity probe. I am sure you will help a lot of people with this post. Not even Neptune’s help desk was this clear.

I was able to calibrate my salinity to work. With your directions. So thank you !

 

[Tastee]

Apex Salinity probes are a pain to calibrate. For the following reasons:

1. Do NOT calibrate if your calibration is already correct. So instead of blindly doing a calibration, first put the probe in the calibration fluid and measure the salinity. If this shows 35 (when temperature is the same as in the tank), THERE IS NO REASON TO CALIBRATE! If its in a range of 34.8-35.2, there is also NO POINT in trying to calibrate it.
2. Most of the time people try to calibrate the using automated calibration option which gives you 0 visibility during the calibration. You should use the manual option instead.
3. Apex calibration is buggy. I noticed when trying to calibrate multiple times in a row it just shows wrong values during calibration, for example a 0 reading for a dry probe. I noticed when resetting the Apex by pulling out the power, it stopped showing that 0 reading. So if you have a reading of 48 salinity or something like that, you might just have calibrated your probe with a 0 reading for a dry probe which is a faulty reading. Should be something in the range of (60-75) for a dry probe and about 538-545 for a probe in calibration fluid of 35 salinity (53.000 mS).
4. A probe measures milivolts mV s which is a tiny measurement and also tiny fluctuations. If you put the probe cable next to ANY other cable, it might return different values. One of the things that you could do it making sure the cable of the salinity probe NEVER goes anywhere near another cable, not even close to the Apex itself. You could also calibrate when lights and gear is off. This should also allow you to calibrate with less interference of other equipment.
5. Air inside the probe causes bad readings. Always turn the probe upside down in the fluid to make sure you do not have any bubbles in it (so turn it upside down in the sump). Obviously you cannot do this in the calibration fluid, but you might cut a corner of the calibration fluid bag, but in the probe, push out as much air as possible and take some tape and tape it off. This will allow you to hold the probe upside down so there will never be any bubbles in it. If you have some experience doing good calibration, it might already be enough to hold the probe at an angle, with the hole up and tap it a few times so air bubbles would go out.
6. ALWAYS LET IT SETTLE FOR AT LEAST 5 MINUTES, except if you know the value you are trying to reach and hit it the first time, but even than it wouldn't hurt to leave it for 5 minutes.

So if you make sure the above 5 points are covered, it will increase the possibility of doing a good calibration.

How to calibrate? As already mentioned, use manual method. Make sure temperature of the calibration fluid and the tank are the same. Make sure it is dry and read the appropriate value (as I mentioned, somewhere between 60-75). Press next, pick the right calibration fluid from the list. Put it in the bag and press next. It should show a value between 538-545. Open up a session of your Apex (but using the local IP address, not the app or apex hostname), so you have a direct connection with the Apex open. That interface is GREY and not the WHITE interface you normally have. You will see the current salinity value based on the current measurement (calibration measurement) and based on the OLD calibration values. This can help you during the calibration.

For example:
I had a bad calibration with a dry probe reading value of 0. Which shows a salinity of 48 when measuring the salinity in my tank. So during the next calibration it would show a value of 35.8 for a settling value of 542. That is because the last calibration was way off, so that is not an issue. Personally I'm looking for a settling value of 542-540 anyway.
When you press save and you had a bad calibration before and if you are a bit lucky, you might see a jump in salinity value. So after calibration (pressing the last Next), I noticed salinity in the second screen (on the Apex directly via the local IP address) a salinity of 31.9, which a few seconds after jumps towards 34.9. What does this mean?
This means that using my bad calibration, the calibration fluid measured a salinity of 35.8 during the calibration (which uses settling numbers from apex itself), although the measurement that was hidden was in fact 31.9 for the calibration fluid (so way off) and a second after when calculation was done using the new settling values, it was changed to 34.9 which is good enough for a calibration fluid of 35.


So what makes it so hard? Lot of things and most likely the combination of all of them.

Thanks, that’s a great summary of your experience and what has worked for you. I’ve saved a note of this for later use!

I’ve seen other posts about how to make a calibration vial you can use which allows you to invert the probe, let me know if anyone wants me to dig up the link.

One very minor point, whether you use the Apex local hostname (apex.local or <whateveryourenameditto>.local or the IP address doesn’t matter - both go to the local dashboard instead of Fusion. You are absolutely right however as this updates probe readings etc immediately without the lag you get in Fusion.

 

[SuncrestReef]

5. Air inside the probe causes bad readings. Always turn the probe upside down in the fluid to make sure you do not have any bubbles in it (so turn it upside down in the sump). Obviously you cannot do this in the calibration fluid, but you might cut a corner of the calibration fluid bag, but in the probe, push out as much air as possible and take some tape and tape it off. This will allow you to hold the probe upside down so there will never be any bubbles in it. If you have some experience doing good calibration, it might already be enough to hold the probe at an angle, with the hole up and tap it a few times so air bubbles would go out.

The best way to calibrate upside down is by using a probe storage bottle:

BRS pH/ORP Probe Tip Soaker Bottle

Store your pH and ORP probes in these convenient bottles - protects the probe during storage. Use with pH/ORP Probe Storage Solution

www.bulkreefsupply.com

Another alternative is to pour the calibration solution into a small plastic bag, insert the probe, then close off the bag with a rubber band around the probe.

With either of these methods, you can tip the probe completely upside down and tap it. All the bubbles will float up out of the probe.

 

[Amado]

Two days later apex salinity probe out of range.

 

[Bramzor]

Two days later apex salinity probe out of range.

As it was on point 2 days ago it's not the calibration. So probably the probe cable is next to or against another cable somewhere. If you have a probe holder, keep one open so you have more space between the probes. Or it might be a bubble in the probe. You might also shut down some gear at night for 30min to see if this has effect on the salinity probe. Water might also carry voltage, although if that would be the case, it should also affect the PH probe.

Really strange that it keeps going up in a straight line. Would be nice to figure out what causes that. It makes me think its not related to it being next to a cable or something because this should follow a signal on that cable and not a straight line... Bubble maybe? Try to change one thing at a time (per day for example) so you can see the result in the graph.

 

[Amado]

As it was on point 2 days ago it's not the calibration. So probably the probe cable is next to or against another cable somewhere. If you have a probe holder, keep one open so you have more space between the probes. Or it might be a bubble in the probe. You might also shut down some gear at night for 30min to see if this has effect on the salinity probe. Water might also carry voltage, although if that would be the case, it should also affect the PH probe.

Really strange that it keeps going up in a straight line. Would be nice to figure out what causes that. It makes me think its not related to it being next to a cable or something because this should follow a signal on that cable and not a straight line... Bubble maybe? Try to change one thing at a time (per day for example) so you can see the result in the graph.

It’s not stray voltage I just moved and the tank is a new setup. I am using 180 tank as a sump. The apex probes have their own section. There is no skimmer on this system yet since there is no real nutrients 4 tangs and 2 clowns in close to 400 gallons of water. I have been battling this in my old tank. The other salinity probe also was flaky.
This is a brand new probe and it still has problems.

 

[Bramzor]

I noticed the last days that I have a stray voltage in at least 2 different cases.



I notice that salinity jumps when my heater is turned on. This heater is a TItanium heater and is in the same area as my salinity probe. I know that this heater has a connection with the earth so this might cause one of the issues. Although I also have another earth pin in the display tank. But if the issue would be the earth connection itself, this connection is always there, even if the heater is NOT so should not only see this issue when the heater is turned on. This makes me think it's not the earth connection but the heater itself or some kind of EMI that it causes.

Besides that, the last peak is one where the heater is NOT on. So this might be caused by the connection with the earth.
Anyway, I might replace the titanium heater and titanium earth pin for a while to see if that makes a difference.

 

[Bramzor]

Figured out the peak, apparently I had some air in the probe caused by the AWC (auto water change) probably. Maybe we should find a way to mount this probe upside down all the time?

 

[Bramzor]

After I did shake some bubbles out of my probe a few weeks ago as reading was a bit off, it started showing a salinity of 50? This salinity was stable for WEEKS at 50, even though I calibrated to probe correctly the last time so I was certain that it had nothing to do with calibration. I was expecting that it would correct itself over time but it didn't.

Today, I took some DSR reference (just plain saltwater that can be used to check different parameters) and probe started showing 33.6 stable in that reference fluid. So I knew calibration was fine and that the probe should show the correct value...

So I put it back in the tank, and it showed a salinity of 34. Go figure!

What we learned today: sometimes if you shake the probe it can show a wrong value for months. Taking it out of the tank and putting it back can just correct the issue.