Help with Apex salinity probe

[All_talk]

If you have it working consistently with the offset, and have measured the tank with something you trust, I think many people have had luck calibrating it to the tank. I have not done this yet because I still need to dial in my TC value, but I suspect I will at least try it.

 

[srobertb]

I don't know answer to your questions, but I will watch this thread as I have the same issue.Perhaps somebody knows the answer. I stopped trusting Apex Conductivity probe and check salinity weekly with Hanna checker. I only look at a trend of Apex probe.
My Apex probe shows today 38.5 ppt and Hanna 36.1ppt and so my refractometer.

Expecting these to work reliably is not a good idea. I have tried the little pump-thing that goes over it that was supposed to “fix it.” No dice. I’ve wasted way too much money on them (I think they need to be replaced like every 3-6 months per most recommendations).

Calibrate it monthly. What you will find is that it can alert you to major issues but trying to dial it in to read correctly and stay there probably won’t happen. Yes, I know some people do, but most do not.

Calibrate it, get a reading, and set an alarm if it changes drastically. Even if it reads 38PPT and your tank is 34PPT, Seeing a drop of 5-10 points or even a steady incline over a couple days will alert you to an issue (but for the latter it probably means the probe is just drifting).

 

[Biologic]

Expecting these to work reliably is not a good idea. I have tried the little pump-thing that goes over it that was supposed to “fix it.” No dice. I’ve wasted way too much money on them (I think they need to be replaced like every 3-6 months per most recommendations).

Calibrate it monthly. What you will find is that it can alert you to major issues but trying to dial it in to read correctly and stay there probably won’t happen. Yes, I know some people do, but most do not.

Calibrate it, get a reading, and set an alarm if it changes drastically. Even if it reads 38PPT and your tank is 34PPT, Seeing a drop of 5-10 points or even a steady incline over a couple days will alert you to an issue (but for the latter it probably means the probe is just drifting).

Again, another user who figured this out---this is the answer. Do not get hung up over it. So many other things to obsess over in this hobby that are more productive. The more you try to "get it perfect", the more frustrated you are going to get.

OP, "perfect is the enemy of good." - Voltaire

Hey here's another story OP. When I was fighting trying to fix this, I broke my $200 probe because I knocked it against the sump accidentally. It's extremely delicate. All it takes it a tap. OP, don't fight this. You are going to have a bad time. This thread should be a sticky as a warning to new comers.

 

[Beazy]

Again, another user who figured this out---this is the answer. Do not get hung up over it. So many other things to obsess over in this hobby that are more productive. The more you try to "get it perfect", the more frustrated you are going to get.

OP, "perfect is the enemy of good." - Voltaire

Hey here's another story OP. When I was fighting trying to fix this, I broke my $200 probe because I knocked it against the sump accidentally. It's extremely delicate. All it takes it a tap. OP, don't fight this. You are going to have a bad time. This thread should be a sticky as a warning to new comers.

I completely agree. The universe gave me a sign today when I broke my second Tropic Marin hydrometer. I’m just gonna use the Hanna, aim for 35ppt and if the fish and coral look good, I’m good.

 

[All_talk]

Just wanted to circle back to this thread and report the results of calibrating to the tank.

Last weekend I got my hydrometer out and checked the tank water and it was right at 1.0255/34.5 ppt/53 mS/cm (my tank runs right at 78 deg F with less than 1 deg variation), so I figured this was my chance. I followed the calibration procedure, but used my tank as the calibration fluid. The results are not only spot on but much more consistent. The first graph includes a portion of the time before the calibration, you can see both the offset and higher variation. The second graph is just the section after calibration, the average is right at the hydrometer reading and the total variation is less than 1 ppt.

It now so consistent I almost distrust it, but my ATO is well tuned (doser pump based) so my tank salinity doesn't really change. I might try raising and lowering a sample of tank water and double checking the reading against the hydrometer. Just for peace of mind.

I'm pretty happy with things at this point.

 

[bestfishes]

It seems I struggle with this every winter when I replace the salinity probe once a year. It gave me a really hard time this week after I removed the probe for a quick cleaning. I should really shift my service interval to summer when all my sollutions will be at 75 room temp ;-). I was reading 38.5 on a tank that i checked with a salinity meter I trust as 36. I tried all the wire tests like isolating the probe wire away from others (eg. power might be getting into the line and impacting the result) but it had no impact on my problem. I have power lines next to probe lines and have for a long time with no issue. I turned the probe upside down and the reading went to 53!! I thought for sure air bubbles were my problem and brushed off each time i submerged into the water and still no dice. I realized the test solution temp was my problem as this time of year the basement is 60 and the tank is 78. I disabled the salt probe, disconnected it, restarted apex, reconncted and then went to town calibrating. I used rodi to rinse and then blew through the hole on the side to remove any trapped water. I floated the testing solution in the tank and left it there during testing so the temp stayed the same. Then I swished the salt probe in the tank water and put in right into the holder. I didnt take too much care on the bubbles, in fact over churning seems to be counterproductive. Now im sitting at 35.8 and I can live with that. It may settle further at this point and hit 36.

 

[Beazy]

It seems I struggle with this every winter when I replace the salinity probe once a year. It gave me a really hard time this week after I removed the probe for a quick cleaning. I should really shift my service interval to summer when all my sollutions will be at 75 room temp ;-). I was reading 38.5 on a tank that i checked with a salinity meter I trust as 36. I tried all the wire tests like isolating the probe wire away from others (eg. power might be getting into the line and impacting the result) but it had no impact on my problem. I have power lines next to probe lines and have for a long time with no issue. I turned the probe upside down and the reading went to 53!! I thought for sure air bubbles were my problem and brushed off each time i submerged into the water and still no dice. I realized the test solution temp was my problem as this time of year the basement is 60 and the tank is 78. I disabled the salt probe, disconnected it, restarted apex, reconncted and then went to town calibrating. I used rodi to rinse and then blew through the hole on the side to remove any trapped water. I floated the testing solution in the tank and left it there during testing so the temp stayed the same. Then I swished the salt probe in the tank water and put in right into the holder. I didnt take too much care on the bubbles, in fact over churning seems to be counterproductive. Now im sitting at 35.8 and I can live with that. It may settle further at this point and hit 36.

I calibrate every 3 months or so and will give this a try when that time comes up at the end of this month. I’d be so happy to get this somewhat close in range again. I want to get a new one and set it up this old one with my water change system if I can get it to act right again