Red Sea Seawater Refractometer

[Myka]

I'm looking for a good quality refractometer with a large scale. You know the Vertex scales?? Tiny. Don't want that. Can hardly tell 1 ppt from the next, and I have good eyes! Currently I have a 20-year old Link refractometer, and it has a great scale! Looking for a second one. :)

Looking at Red Sea's website, it appears that the scale is larger than the Vertex scale. Could someone please confirm that? I tried this thread in the equipment forum, but no answer.

 

[don_chuwish]

You got me interested, so I found this:
https://reefbuilders.com/2014/05/14/recommend-red-seas-refractometer-measuring-aquarium-salinity/#

 

[Myka]

You got me interested, so I found this:
https://reefbuilders.com/2014/05/14/recommend-red-seas-refractometer-measuring-aquarium-salinity/#

Yes, I've read that before. They've really fluffed it up to make it sound a lot more amazing than it is. Hehe. It's just a seawater refractometer with automatic temperature compensation. They go on about the Red Sea being calibrated at the right temperature, blah blah. Sure, that's great for the calibration out of the box, but you're going to calibrate it a million times in the life of it I would hope! Hehehe. :)

You do know that Reef Builders is paid advertisements, right? :D

 

[SPR1968]

I'm looking for a good quality refractometer with a large scale. You know the Vertex scales?? Tiny. Don't want that. Can hardly tell 1 ppt from the next, and I have good eyes! Currently I have a 20-year old Link refractometer, and it has a great scale! Looking for a second one. :)

Looking at Red Sea's website, it appears that the scale is larger than the Vertex scale. Could someone please confirm that? I tried this thread in the equipment forum, but no answer.

I've got the Red Sea Refractometer and it's a quality piece of kit and very easy to read the scale in both 1.026/35ppm formats

You just need to make sure you calibrate it before every use, and I mean every use, to get its accuracy. I know this because I just used it out of the box without calibration (when I started out) and had all sorts of swings in salinity readings.

The calibration takes seconds so it's not an issue and I use mainly 0 RODI but also have some 35ppm calibration fluid although rarely use that.

 

[Myka]

Wow, is it off every time you calibrate it? Maybe you got a dud?

 

[SPR1968]

Wow, is it off every time you calibrate it? Maybe you got a dud?

No it's not a dud, I just think they are very sensitive maybe to temperature etc. The calibration does take just a few seconds though and it's only usually very minor. Alternatively just look we're the 0 line is with RO and take it into account when the tank waters added.

When I first got it I thought it would just work out of the box (was my first one) and had salinity up and down, was dumping salt in, taking it out etc and then I spoke to Red Sea, and they said 'you are calibrating it each time aren't you'? Mmmm. Of course I said yes lol.

Never had a problem with it since doing this and the salinity is usually spot on with very little need for adjustment up or down

 

[Myka]

Oh they even suggested daily calibration? Wow. Ok. I don't like opening the calibration fluid that often, but for $5 it can be replaced more often. :)

 

[SPR1968]

Oh they even suggested daily calibration? Wow. Ok. I don't like opening the calibration fluid that often, but for $5 it can be replaced more often. :)

You can calibrate the zero point with 0 RODI which is what I do. You just put a few drops on the glass, zero it if needed and then just wipe it clean and your good to go with tank water.

I also have a jar of 35ppm calibration fluid but hardly ever use that as the RO water is fine.

 

[FishGuyBri]

I calibrated mine daily for a few weeks and made only one adjustment, so I switched to weekly calibration and I usually adjust it less than 1 ppt

 

[SPR1968]

I calibrated mine daily for a few weeks and made only one adjustment, so I switched to weekly calibration and I usually adjust it less than 1 ppt

That's right - we're not talking major adjustments normally just minor adjustments if need be and it's not always necessary. I've just used it and it didn't need adjusting at all. I've found it's normally when there are temperature swings such as summer months here in the UK.

I don't normally check the salinity daily anyway, so it's normally once or twice a week which is fine.

 

[p7willm]

The problem calibrating at 0 is you want to measure somewhere else. If you are lucky the instrument is linear from where you calibrate to where you measure. If you calibrate about where you want to measure it is one more potential error you remove.

Also be careful cause refractometers are designed to measure different things, and none of them measure how many things there are in water directly. A refractometer can be designed to determine how much salt is in water or how much stuff is in sea water and they will give different readings on tank water if they are calibrated at 0.

 

[SPR1968]

The problem calibrating at 0 is you want to measure somewhere else. If you are lucky the instrument is linear from where you calibrate to where you measure. If you calibrate about where you want to measure it is one more potential error you remove.

Also be careful cause refractometers are designed to measure different things, and none of them measure how many things there are in water directly. A refractometer can be designed to determine how much salt is in water or how much stuff is in sea water and they will give different readings on tank water if they are calibrated at 0.

Yes I agree with you on this, it's just that on my Red Sea for example, I've calibrated on the same occasion with both 0 RO and 35ppm fluid and it's in line on both which is why I mainly just use RO as I'm confident with the calibration using that is ok.

If your not sure, or in doubt I would always just use 35ppm or whatever calibration fluid.

 

[Myka]

The problem calibrating at 0 is you want to measure somewhere else. If you are lucky the instrument is linear from where you calibrate to where you measure. If you calibrate about where you want to measure it is one more potential error you remove.

Also be careful cause refractometers are designed to measure different things, and none of them measure how many things there are in water directly. A refractometer can be designed to determine how much salt is in water or how much stuff is in sea water and they will give different readings on tank water if they are calibrated at 0.

The Red Sea refractometer removes this issue. Most of the refractometers in the hobby are BRINE refractometers. The Red Sea refractometer is a TRUE SEAWATER refractometer. The whole point in upgrading to this particular brand of instrument is because of the linear measurement in seawater. The other good thing is that you can dual-point calibrate both at 0 ppt and 35 ppt to assure the calibration solution and the instrument are accurate, where brine refractometers cannot be dual-calibrated and MUST be calibrated at 35 ppt. :)