Which salinity reading is right?!

[Marco S]

Salinity shouldn't fluctuate that much. The two biggest influencers are evaporation and the mix point of your water when you do water changes. Trying to monitor it with the Apex probe will just leave you chasing phantoms ...

Thats' the main reason to monitor it though...because it should not fluctuate. If it does, then something is wrong and you need to know about it. For example, I religiously forget to turn my ATO back on after water changes and when the salinity raises the next day I get an alarm and remember to turn the ATO back on. That's just one example, but it can be a life saver if something more serious were to cause a swing.

 

[foxt]

Thats' the main reason to monitor it though...because it should not fluctuate. If it does, then something is wrong and you need to know about it. For example, I religiously forget to turn my ATO back on after water changes and when the salinity raises the next day I get an alarm and remember to turn the ATO back on. That's just one example, but it can be a life saver if something more serious were to cause a swing.

True, but there are other ways to monitor for stuff like that. What I learned when I fiddled with a salinity probe when I first started playing with controllers was that when it was fluctuating, it was usually because the probe itself was the issue.

You've found a way to make it work for you - is there an acceptable range/tolerance that you code for and raise an alarm when it gets over that?

 

[HOOPDEEZ]

I will concur, that my apex salinity probe is off by 2ptt, but it is consistent, so you can watch for fluctuations. FWIW I agree that a refractometer with calibration fluid (vs rodi) is a good baseline.

 

[DS204]

I will concur, that my apex salinity probe is off by 2ptt, but it is consistent, so you can watch for fluctuations. FWIW I agree that a refractometer with calibration fluid (vs rodi) is a good baseline.

Thanks for this. We'll probably use it just for watching variations and fluctuations like you suggested.

About calibrating - the Red Sea refractometer suggests to calibrate using RODI water in their instructions. The neptune calibration fluid states on the package that it shouldn't be used to calibrate refractometers, but I have no clue why. The Hanna calibration fluid says on the package that it's only for the hanna checker.

It doesn't make sense to me why they can't be used between brands. I would have thought that a 35ppt salinity standard is just that - a standard. But, maybe they are unique to their own brands? A mystery to me, that's for sure!

 

[foxt]

It doesn't make sense to me why they can't be used between brands. I would have thought that a 35ppt salinity standard is just that - a standard. But, maybe they are unique to their own brands? A mystery to me, that's for sure!

This is an interesting read:

Does your calibration solution need calibrated?

One of the very basic parameters that we need to maintain is that of salinity which can directly and indirectly effect all other parameters. http://reef2reef.com/threads/optimal-parameters-for-a-coral-reef-aquarium-by-randy-holmes-farley.173563/ Being able to accurately test for and read what...

www.reef2reef.com

I don't rely on a single standard to calibrate my refractometer ...

 

[DS204]

This is an interesting read:

Does your calibration solution need calibrated?

One of the very basic parameters that we need to maintain is that of salinity which can directly and indirectly effect all other parameters. http://reef2reef.com/threads/optimal-parameters-for-a-coral-reef-aquarium-by-randy-holmes-farley.173563/ Being able to accurately test for and read what...

www.reef2reef.com

I don't rely on a single standard to calibrate my refractometer ...

Someone referred to me to this thread before, and it looks like an interesting extension of the hobby that unfortunately I'm not ready to pursue yet. I'm going to rely on this Hanna checker and when I run out of calibration solution in about 6 months I'm going to explore this link you & someone else referred me to.

Thank-you for your input & help!

 

[HOOPDEEZ]

The Neptune calibration liquid is for a conductivity probe, so it should not be used for a refractometer. Not familiar with the hanah salinity checker, but you can buy refractometer calibration fluid a number of different places, including brs. Maybe the Red Sea refractometer is different, but if I use rodi to calibrate mine, and then use a 35ppt standard, the reading will be off. I figure I want it to be accurate at 35ppt and don’t really care about 0ppt

 

[DS204]

The Neptune calibration liquid is for a conductivity probe, so it should not be used for a refractometer. Not familiar with the hanah salinity checker, but you can buy refractometer calibration fluid a number of different places, including brs. Maybe the Red Sea refractometer is different, but if I use rodi to calibrate mine, and then use a 35ppt standard, the reading will be off. I figure I want it to be accurate at 35ppt and don’t really care about 0ppt

OK noted, thanks for this. I'm going to pick some of that up next time we order from BRS. Thanks!

 

[DS204]

If a moderator wants to close or lock this thread, please do.

I'm satisfied with the responses that everyone shared here and I left with more information than I started with, so thanks!

 

[Bensonthefish]

Glad to have found this post. I just got the apex last week which came with the salinity probe. I have the same +5ppt delta over the Hana digital tester. First I had issues linking my apex to android. Took me the whole day researching and found another post where they connected first with IOS. Did the same and now am able to connect via android. 2 negatives so far for a $1.4k toy.....bummer...

 

[Tim McLellan]

Call me a naive simpleton, but I've only ever used an Instant Ocean swing arm hydrometer. Very basic device, nothing complicated and never has to be calibrated. I've had no issues figuring out what my salinity is. 7 months in and all fish, corals and CUC seem perfectly happy. Very satisfied with the state of my tank.