Salinity Impossible to read

[ThatsNoMoon]

Hello all,

I cannot tell what my salinity is. Let me explain:

I have a cheap refractometer, a red sea branded one and a brand new (arrived today) Hanna salinity tester.

I have used the Hanna calibration liquid on the Hanna checker and RO/DI on the refractometers.

Calibrated on RO/DI:
Refractometer reads tank at 33ppt (and reads refractometer at 40ppt)

Calibrated on Brightwell 35ppt Calibration fluid:
refractometer reads tank at 30ppt

calibrated on Brightwell 35ppt fluid 2nd bottle:
refractometer reads tank at 28ppt

Hanna freshly calibrated:
Hanna read tank at 33.5ppt


My refractometers read the Hanna calibration solution at 25ppt
My Hanna checker reads my Brightwell calibration solution at 40ppm


I have no idea what numbers to trust or read

 

[NeonRabbit221B]

Does the cover move freely and rest evenly on the lens surface? If that isn't laying flat and can't move freely that could be the cause of your issues.

This is exactly the reason why I went digital.

 

[ThatsNoMoon]

Does the cover move freely and rest evenly on the lens surface? If that isn't laying flat and can't move freely that could be the cause of your issues.

This is exactly the reason why I went digital.

it does and I read similar numbers on my cheaper refractometer too. I have no idea what to trust at this point

 

[alysak6075]

Create your own sample: Use the directions on the salt container, make a gallon of water.

Whichever device gets close to what the directions indicate it should be: WINS.

 

[NeonRabbit221B]

The hanna check solutions... are they for the digital reader?

 

[ThatsNoMoon]

The hanna check solutions... are they for the digital reader?

yes so I just found out the digital reader's calibration liquid does not work on the refractometer. I still get inconsistent readings from the refractometers though which is unfortunate

 

[littlebeard]

Did the digital refractometer come with a reference fluid? Do you have any other reference fluids?

Are you cleaning the digital reader off properly? I know I need to put some rodi on mine and wait for a minute for it to soak up any salt from the previous test that I missed. Is it consistently off?
Are your pipettes cleaned properly?


I love my Milwaukee digital refractometer, I can't ever get consistent readings with the handheld ones assuming I can read the little lines.

 

[NeonRabbit221B]

The main thing is consistency and stability. Choose one and go with it. Better yet, buy a new solution and toss the rest

 

[Reef.]

A lot of people have found the calibration fluids to be off, 2 different bottles can read differently.

Make your own, you need 0.01g scales, $20 on Amazon, 3.65g of table salt mixed in 96.35g rodi water.

If your Hanna is still reading wrong after making your own calibration fluid you may find it’s just incorrect, some people do not rate them.

With any luck it turns out to be correct, if not the Tropic Marin Hydrometer is as accurate as you are likely to get.

 

[ThatsNoMoon]

Did the digital refractometer come with a reference fluid? Do you have any other reference fluids?

Are you cleaning the digital reader off properly? I know I need to put some rodi on mine and wait for a minute for it to soak up any salt from the previous test that I missed. Is it consistently off?
Are your pipettes cleaned properly?


I love my Milwaukee digital refractometer, I can't ever get consistent readings with the handheld ones assuming I can read the little lines.

the Hanna did some with 4 testing fluids and i tried 2. both read 35

I clean it all very well and pipettes and rinsed in the liquid I'm trying to get a reading from to make sure it drips an undiluted solution onto the refractometers.

All of them are consistently their own results and none of them match each other which is why i'm so lost. I think the RO/DI -Refractometer reads my Hanna as the same result so I will stick with that and assume my calibration liquids are garbage

 

[ThatsNoMoon]

A lot of people have found the calibration fluids to be off, 2 different bottles can read differently.

Make your own, you need 0.01g scales, $20 on Amazon, 3.65g of table salt mixed in 96.35g rodi water.

If your Hanna is still reading wrong after making your own calibration fluid you may find it’s just incorrect, some people do not rate them.

With any luck it turns out to be correct, if not the Tropic Marin Hydrometer is as accurate as you are likely to get.

Made the mix:

Refractometer reads 33/34
Hanna: 38

 

[vetteguy53081]

I test both of my units and take a sample to LFS and have them test to see which is a match
Fortunately, both of mine are close in reading to each other

 

[ThatsNoMoon]

Thanks everyone for the replies.

I have a cheap swing arm salinity tester coming in the post and the floating tropic marine one (may come very late due to covid so i ordered both)

If i calibrate the Refractometer using RO/DI then it reads very closely to the Hanna so I'm going to stick with them and wait for the other testers to come. At the moment my salt should not massively impact on the welfare of my coral or fish so I will try not to mess with it

 

[Reef.]

Thanks everyone for the replies.

I have a cheap swing arm salinity tester coming in the post and the floating tropic marine one (may come very late due to covid so i ordered both)

If i calibrate the Refractometer using RO/DI then it reads very closely to the Hanna so I'm going to stick with them and wait for the other testers to come. At the moment my salt should not massively impact on the welfare of my coral or fish so I will try not to mess with it

just keep in mind the hydrometer needs the water to be at 25c before testing, if it isn’t you have to use a chart to get the correct salinity, a measuring cylinder comes in handy too.

 

[William Morris]

A lot of people have found the calibration fluids to be off, 2 different bottles can read differently.

Make your own, you need 0.01g scales, $20 on Amazon, 3.65g of table salt mixed in 96.35g rodi water.

If your Hanna is still reading wrong after making your own calibration fluid you may find it’s just incorrect, some people do not rate them.

With any luck it turns out to be correct, if not the Tropic Marin Hydrometer is as accurate as you are likely to get.

Do you have a reference for the scale on Amazon?

 

[mindme]

Create your own sample: Use the directions on the salt container, make a gallon of water.

Whichever device gets close to what the directions indicate it should be: WINS.

I personally would not do this.

 

[Reef.]

Do you have a reference for the scale on Amazon?

I’m in the UK so probably won’t help you.

Just type in 0.01g scales and get the best viewed one.

 

[no1baggiesfan]

A lot of people have found the calibration fluids to be off, 2 different bottles can read differently.

Make your own, you need 0.01g scales, $20 on Amazon, 3.65g of table salt mixed in 96.35g rodi water.

If your Hanna is still reading wrong after making your own calibration fluid you may find it’s just incorrect, some people do not rate them.

With any luck it turns out to be correct, if not the Tropic Marin Hydrometer is as accurate as you are likely to get.

do you actually use that mix to calibrate with ?

I just tried making it and my refractometer was off the scale, id guess somewhere around 80ppt lol

 

[Reef.]

do you actually use that mix to calibrate with ?

I just tried making it and my refractometer was off the scale, id guess somewhere around 80ppt lol

Yes, are your scales 0.01g?

You need to be accurate, even a couple of extra drops of water or grains of salt will throw off the results, probably best to actually weight the ingredients on the scales, so zero a container on the scales then add the water, measure exactly 96.35g, then add the salt.

If you are still having issues you can double or triple the measurements, making a larger amount will help minimise are errors.

 

[Randy Holmes-Farley Verified Community Expert]

do you actually use that mix to calibrate with ?

I just tried making it and my refractometer was off the scale, id guess somewhere around 80ppt lol

Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com