Measuring Salinity

[Instigate]

How often do you calibrate your refractometer? Comment what type you use.

I have been using an ATC refractometer and calibrated it a few times. Thought all was well. But then my cal/alk/mag drifted down and I thought it was my corals using it up so I brought levels back up with two part and started using kalk. I only have like 15 or so small frags in a 135g system so I wasn't expecting to have to dose anything so soon. Then I realized my refractometer was way out of calibration. So I calibrated and slowly brought everything back to normal. My parameters are all good now and I'm calibrating the refractometer every time I use it. But I'm noticing that I will calibrate it and it will end up out of calibration in between tests and I'm having to calibrate it several times each use. Is that normal? Seems doubtful. Do I need a new one? I've seen some that cost a couple hundred instead of $15 or so, I assume those more expensive models will stay calibrated longer? Or if I'm paying that much I might as well go for the Milwaukee digital refractometer I guess. How often do those need calibration?

 

[Jeff Hall]

I had the same issue with my refractometer. Is yours made by Red Sea? Ended up forking out the money to get a digital one. Well worth the price by the way.

 

[Crabs McJones]

I use an ATC Refractometer as well. And I calibrate mine everytime before use because why not? Never hurts to be to sure

 

[chipmunkofdoom2]

I had the same issue with mine (I had the one from BRS). I ended up switching to the Pinpoint Salinity Monitor. Having used it for over a year and a half, I have to say I much prefer measuring conductivity over measuring refractive index.

 

[Fudsey]

I use the ATC from BRS as well but that new pen is looking very tempting

 

[Randy Holmes-Farley Verified Community Expert]

I voted never because I have never used one for this purpose (but have for other scientific purposes).

I prefer conductivity to measure salinity. Good floating glass hydrometers are also a good choice.

 

[Fudsey]

Good floating glass hydrometers are also a good choice.

Randy, I have one of these and it is off by more than .003 on the low side compared to my refractometer. Granted it is an inexpensive one but still...

 

[Randy Holmes-Farley Verified Community Expert]

Randy, I have one of these and it is off by more than .003 on the low side compared to my refractometer. Granted it is an inexpensive one but still...

What brand? Did you correct for temperature issues? Since it cannot ever deviate in calibration, one check of it in its lifetime should be sufficient, then just make that correction each time.

Not many people use glass hydrometers any more. I stopped when I broke my Tropic Marin.

 

[Fudsey]

Aquatic Gardens, if that means anything. Like I said it was just a cheapo to try out before my refractometer came in. Temp was always 78 when I tried it. Before that I was using a hydrometer (plastic) and that was off by more. That's why I turned to a refract. instead. And I use 35 solution from BRS to calibrate every use

 

[Instigate]

I had the same issue with my refractometer. Is yours made by Red Sea? Ended up forking out the money to get a digital one. Well worth the price by the way.

I got mine on amazon. It's not branded red sea.

I had the same issue with mine (I had the one from BRS). I ended up switching to the Pinpoint Salinity Monitor. Having used it for over a year and a half, I have to say I much prefer measuring conductivity over measuring refractive index.

I'll have to check that out!

 

[siggy]

my first one did not come with calibration fluid and by the time I had some the cal screw was rusted and in-op, Its barley 1 point now . I purchased a Milwaukee and zero with rodi and check with .35 calibration solution
and that consistently reads .34 checked against BRS cal solution from my new refractometer and still the same so I still double check and offset by 1.
That new Ice cap temp & salinity pocket probe sounds tempting, I'll bet it will be off by 1 also

 

[Randy Holmes-Farley Verified Community Expert]

Aquatic Gardens, if that means anything. Like I said it was just a cheapo to try out before my refractometer came in. Temp was always 78 when I tried it. Before that I was using a hydrometer (plastic) and that was off by more. That's why I turned to a refract. instead. And I use 35 solution from BRS to calibrate every use

OK, thanks.

 

[chipmunkofdoom2]

Now that there's a poll in this thread, I voted "every time." That was, however, when I used my refractometer. As I said in a previous post, I've since upgraded to a Pinpoint Salinity Monitor. I calibrated it when I got it and haven't had to change the calibration since. I check every month or so to make sure it's still accurate, and it's still perfectly calibrated.

 

[siggy]

Now that there's a poll in this thread, I voted "every time." That was, however, when I used my refractometer. As I said in a previous post, I've since upgraded to a Pinpoint Salinity Monitor. I calibrated it when I got it and haven't had to change the calibration since. I check every month or so to make sure it's still accurate, and it's still perfectly calibrated.

Thanks going to check it out

 

[2una]

Good floating glass hydrometers are also a good choice.

I don't know why their not more popular
I went from refractometer to digital & now glass floater, i find the glass floater the best hence also my "never" vote
Nice & easy to read with wide spaced markings

 

[Instigate]

Just ordered a few glass hydrometers. But still curious about the conductivity salinity meters.

I voted never because I have never used one for this purpose (but have for other scientific purposes).

I prefer conductivity to measure salinity. Good floating glass hydrometers are also a good choice.

Would you be able to make any recommendations on specific products? I'm seeing cheap pocket salinity meters but I get the feeling they're probably not what you're referring to.

https://www.amazon.com/Hydroponics-...rd_wg=wxF0I&psc=1&refRID=47SBBW1N7QR3RZ6574BF

https://www.amazon.com/dp/B072B5JDK...olid=3W3GOR8V1ZSEX&psc=0&ref_=lv_ov_lig_dp_it

https://www.amazon.com/LaMotte-1749...rd_wg=wxF0I&psc=1&refRID=47SBBW1N7QR3RZ6574BF

And then once I'm up over $100 I would consider these:

https://www.bulkreefsupply.com/milwaukee-digital-seawater-refractometer.html

https://www.bulkreefsupply.com/pinpoint-salinity-monitor.html

 

[Daltrey]

I use two refractometers. If they are ever off from each other then I will recalibrate them. So far that has never happened. I do have a small bottle of calibration fluid if I ever need it.

 

[Instigate]

I use two refractometers. If they are ever off from each other then I will recalibrate them. So far that has never happened. I do have a small bottle of calibration fluid if I ever need it.

I think I must have knocked mine too hard because it's out of calibration literally every time I use it. And I'm finding myself having to calibrate it multiple times when trying to get readings from multiple tanks.

 

[Daltrey]

I think I must have knocked mine too hard because it's out of calibration literally every time I use it. And I'm finding myself having to calibrate it multiple times when trying to get readings from multiple tanks.

Mine have a nice foam padded hard shell case I keep them in. I will keep in mind not to bump them hard into anything. Thanks

 

[Randy Holmes-Farley Verified Community Expert]

Just ordered a few glass hydrometers. But still curious about the conductivity salinity meters.



Would you be able to make any recommendations on specific products? I'm seeing cheap pocket salinity meters but I get the feeling they're probably not what you're referring to.

https://www.amazon.com/Hydroponics-...rd_wg=wxF0I&psc=1&refRID=47SBBW1N7QR3RZ6574BF

https://www.amazon.com/dp/B072B5JDK...olid=3W3GOR8V1ZSEX&psc=0&ref_=lv_ov_lig_dp_it

https://www.amazon.com/LaMotte-1749...rd_wg=wxF0I&psc=1&refRID=47SBBW1N7QR3RZ6574BF

And then once I'm up over $100 I would consider these:

https://www.bulkreefsupply.com/milwaukee-digital-seawater-refractometer.html

https://www.bulkreefsupply.com/pinpoint-salinity-monitor.html

My recommendation would be the Pinpoint, or a used Orion conductivity meter on ebay.