Issue with salinity and calibration

[rmorris_14]

So let first say everything in my tank is doing fine.
:::sigh::: I don’t know what to believe anymore with my salinity checkers.
I was calibrating my refractometer with distilled water (yes I know this not the preferred method). My refractometer was reading different salinities than the hydrometer I had. So I purchased a second hydrometer to see if I could get two to match. Well the brand new one read a completely different salinity than either.
::::::sigh::::
So I purchased accurasea seawater calibration solution.
it said my refractometer was like 5 ppt off. And my tank water is actually around 1.023 instead of 1.026.
I tried using the calibration solution with the hydrometers and it shows like 40ppt.
I don’t know what to believe anymore. I don’t want to increase my salinity based off the accurasea calibration fluid if it is off and make my salinity stupid high.
besides suggesting I go out and spend over $100 for a digital one (that’s just not an option right now)
Or telling me to take it to a trusted LFS to test (I don’t have one of those)
What would you do? Feeling very discourage right before I water change.

 

[blaxsun]

I never had luck with my Hanna salinity tester, so I just bought a cheap refractometer (used the AccuraSea stuff as well) as a reference. I mainly use my Neptune salinity probe to monitor results and will occasionally take a water sample into my LFS to have them use their expensive digital one to see if I'm off.

Given my own experience, I would probably trust the refractometer over the hydrometer - especially if you've calibrated it correctly. The other things I could suggest aren't necessarily availabke as options for you.

 

[rmorris_14]

Do you bring your calibration solution to tank water temp? I just did that and it matched closer to what I thought it should be hmmmmmmmmmm

 

[ReeferCPA]

My 2 cents. Consistency and stability is the key here. Pick a measurement tool and never use the others again. Just choose the tool you have the highest confidence in, and continue to use that. (I would lean towards the refractometer since you have it)

Fish and coral don’t care if your tank is 1.026 or 1.024, they just want it to stay the same. Stability will take you a lot further than number chasing.

 

[Sean Clark]

Do you bring your calibration solution to tank water temp? I just did that and it matched closer to what I thought it should be hmmmmmmmmmm

I always make sure my measurement samples and calibrations are all performed at 78 deg for this very reason. The more consistent the procedure the more consistent the results.

 

[Reefer Reboot]

https://www.bulkreefsupply.com/high..._gVuiTK5VGLRh4TkdIKMsEcpelBrONEhoCraEQAvD_BwEThe most accurate and consistent "measuring device" I have come across. Mix your water to what you want using this, then calibrate your refractometer to match. Use the refractometer for spot checks but verify the calibration every so often with the hydrometer.

 

[rmorris_14]

Ok but do you guys have to calibrate often? My refractometer won’t hold calibration. It floats within 1 day.. is that normal?

 

[Sean Clark]

I calibrate my Hanna digital refractometer (not the handheld unit) every time that I use it. This is easy because it only requires a few drops of water. I like the ability to calibrate the product without needing to purchase over inflated calibration solutions. This is a positive situation all around.

 

[Reefer Reboot]

I have only needed to calibrate my refractometer one time using the above method I posted and it is holding true. What are you calibrating yours with?

 

[bruno3047]

I calibrate my refractometer to 0 TDS RO water. Never had a problem and I have no idea why I would. I don’t even think about using a Hydrometer any more. My RO water registers a perfect 7 on the pH scale. Sometimes you can just over analyze things.

 

[Doctorgori]

My 2 cents. Consistency and stability is the key here. Pick a measurement tool and never use the others again. Just choose the tool you have the highest confidence in, and continue to use that. (I would lean towards the refractometer since you have it)

Fish and coral don’t care if your tank is 1.026 or 1.024, they just want it to stay the same. Stability will take you a lot further than number chasing.

totally true but you dont want to be “consistently” out of range for months and months, not with salinity anyway….somethings can adapt to and survive long term in low salinity, other things can’t …. I’m thinking of all things measured, salinity being accurate to a standard would matter

 

[Sean Clark]

 

[Geebs19]

I calibrate my refractometer to 0 TDS RO water. Never had a problem and I have no idea why I would. I don’t even think about using a Hydrometer any more. My RO water registers a perfect 7 on the pH scale. Sometimes you can just over analyze things.

I do the same thing with 0 TDS water. I don’t use calibration fluid.

 

[bruno3047]

Ok but do you guys have to calibrate often? My refractometer won’t hold calibration. It floats within 1 day.. is that normal?

If I’m handling mine a lot, like mixing multiple buckets of water, it might go out of calibration, but not enough to make a difference. Like .0005, So instead of showing 1.025, I’ll get 1.0255. If your refractometer is losing calibration just because it feels like it, maybe you need a new one.

 

[Reefer Reboot]

For a true calibration you will need to have two data points. The first one would be the starting point (AKA zero) which is controlled by an offset adjustment. The second would be at the full range that you are going to (AKA span or gain) which would be dialed in by the gain adjustment. Since the refractometers (that I've seen) only have an offset adjustment, it is best to calibrate it to the known desired salinity.

 

[rmorris_14]

For a true calibration you will need to have two data points. The first one would be the starting point (AKA zero) which is controlled by an offset adjustment. The second would be at the full range that you are going to (AKA span or gain) which would be dialed in by the gain adjustment. Since the refractometers (that I've seen) only have an offset adjustment, it is best to calibrate it to the known desired salinity.

Hahaha I didn’t get any of that except the last part. Wilhich I do use sea water calibration solution to calibrate to desired salinity .

 

[rmorris_14]

Hahaha I didn’t get any of that except the last part. Wilhich I do use sea water calibration solution to calibrate to desired salinity .

It’s probably the Titos ;)

 

[Sean Clark]

Is this going to go that way?... count me in.

 

[rmorris_14]

Is this going to go that way?... count me in.

 

[rmorris_14]