Best refractomer

[abinder]

The manual itself says you can use distilled or deionized. Its on page 9 of the user's guide If i'm not mistaken. It also notes at the bottom of the page that if the device is shut off, the calibration still remains.

That would not be correct. Someone might say it. Even the manufacturer might say it, but it is wrong.

Hmmmmmmmmmm..............and why is it wrong if the manufacturer says it?
Is there a difference between plain DI water and RO/DI water?
Has anyone actually tried to see if they get a different reading when calibrating with RO/DI water and comparing it to a calibration using "steam-distilled" water?


Allen

 

[tankstudy]

Hmmmmmmmmmm..............and why is it wrong if the manufacturer says it?
Has anyone actually tried to see if they get a different reading when calibrating with RO/DI water and comparing it to a calibration using "steam-distilled" water?

I have done it with both and compared them, there doesn't appear to be any difference at all.

 

[Randy Holmes-Farley Verified Community Expert]

Hmmmmmmmmmm..............and why is it wrong if the manufacturer says it?
Is there a difference between plain DI water and RO/DI water?
Has anyone actually tried to see if they get a different reading when calibrating with RO/DI water and comparing it to a calibration using "steam-distilled" water?

I hope no one has wasted their time on that. [edit, I see at least one person did ]

Unfortunately, manufacturers often do not understand their products and give incorrect directions. That is true for many of the big name product lines (Brightwell, Kent, Carib Sea, etc.) for a variety of products, and, in this context, many resellers of refractometers supply incorrect directions for the refractometers they sell.

No, there is no difference between RO/DI water and distilled water in this context. Even improperly made RO/DI water with, say 5 ppm TDS does not have a refractive index enough different from totally pure water to be detectable with any of the refractometers sold to hobbyists. The difference in specific gravity units would be approximately 1.000000 vs 1.000004. Unless you can distinguish that on your refractometer (and none can) then it cannot matter.

 

[jason2459]

For what I use on a normal basis:

My favorite by far and I feel is my most dependable testing device is my Veegee/Vitalsine. They are both the same. The Filter Guys sell the Veegee and other places sell it labeled as VitalSine. Same refractometer just relabeled and only on the outside. You look in the optics and it's the veegee label you see. I use a calibration fluid on it periodically but rarely do I have to actually calibrate it. It's been well over a year since I had to calibrate it. It's a very clear, bright, and distinct line. It is a true seawater refractometer and can be calibrated to 0 with RO/DI but I still use a 35ppt standard.

My second favorite is my PinPoint Salinity probe that I use for my Saltmix bin. Easy to adjust and couldn't be easier to read. I will still use my Veegee as a double check at the end before putting the saltmix to use in my automatic water chance system.

I also use consistently is the Apex Salinity Probe. (I used to have a reefkeeper and it's salinity probe was much worse) I don't really depend on an exact reading from it as there's a lot that can interfere with it's readings. But I do like it as a general check and a failsafe used for my ATO and AWC. If salinity is to low it stops my AWC. If it's to low it will also switch my ATO from using my RO/DI resevour and pull from my large bin of new saltwater used for AWC then switches back to my normal RO/DI container once elevated. If it's to high it stops my AWC. It's numbers do swing up and down through out the day so my threshholds are rather broad. My low point is 32ppt and my high point is 36.5ppt. It tends to drift lower then higher.

I also have a Milwakee digital refractometer that got all sorts of praise at the beginning of this thread and will most likely after this post as well. It's very easy to use and of course very easy to read as it's digital. It only calibrates to 0 and I do use RO/DI before each use though not necessary. I have it right there in front of me when I do use it so I do use it. I do find that it reads high. For example, I've been doing a lot of comparison testing lately and my major sampling using all my devices my Veegee read a 35ppt standard as 35ppt. My Milwakee as 36ppt. My tank water reading via my Veegee was 34ppt and by the Milwakee as 36ppt. Via Triton's analysis and calculated out to 33.96ppt.

What I don't use anyore but have or had:

A cheap generic $30 refractometer from BRS, Marine Depot, and Ebay. Yep, I've tried out three different cheap refractometers. All were just fine actually. Just needed calibrated every month to couple of months. Regardless of what the manual says they can NOT be calibrated to 0 with RO/DI and I played around with testing that out and of course Randy is perfectly right in his refractometer articles. They are off when tested against 35ppt standard. They also needed longer to adjust for temp but they were ATC. They were all about the same in clarity which wasn't bad but not near as clear as the Veegee. Often the blue line would be doubled or blured.

I also have a DD H2Ocean refractometer. It's a seawater refractometer and can be calibrated to 0. I don't trust it's marking at 0 as much as it's not a full scale leading to 0. If you happen to use hyposalinity for QT then this refractometer would not work. Otherwise it held its calibration well but was a bit darker visually then the veegee.

My least favorite device by far is the Red Sea seawater refractometer. I threw it in the trash. I still have the case I use for my veegee as it either didn't come with one or I can't find it. I can't remember. It's scale seemed squished and double lined making it harder to read. It also was HORRIBLE at staying calibrated. The El Cheapo refractometers did a better job and were easier to read.

 

[tankstudy]

I hope no one has wasted their time on that. [edit, I see at least one person did ]

lol.

 

[Randy Holmes-Farley Verified Community Expert]

My second favorite is my PinPoint Salinity probe that I use for my Saltmix bin. Easy to adjust and couldn't be easier to read. I will still use my Veegee as a double check at the end before putting the saltmix to use in my automatic water chance system.

Very nice summary.

FWIW, I also like conductivity, and I prefer it to a refractometer.

You can get hands off readings in real time (such as in acclimating a fish), and you can measure things a refractometer cannot (such as limewater potency).

I use an Orion Model 128 (expensive) and the Pinpoint. The major difference I've seen between these two is the Orion comes to a stable reading much faster (because it reads temperature faster), but in general, both have been perfectly adequate for salinity and other purposes.

 

[clee36]

am i the only one that uses and likes the redsea refractometer?
i can relate to the calibration issues on it, but why wouldnt you calibrate it before you use it anyway?

 

[Lenny_S]

am i the only one that uses and likes the redsea refractometer?
i can relate to the calibration issues on it, but why wouldnt you calibrate it before you use it anyway?

I use the Red Sea refractometer and I like it fine. I do calibrate it before each use and most of the time it doesn't need to be adjusted. Perhaps that's because I store it in my stand where the ambient temperature stays very constant. Accuracy wise it's very good, I compared it to a digital salinity probe I borrowed, and got the same reading. I couldn't tell you if it is "the best" out there, but it does the job, is easy to use, and was fairly inexpensive.

 

[Nick Marchese]

It seems the conclusion is that they are all the same.

 

[jason2459]

It seems the conclusion is that they are all the same.

Not really all the same but all will work just fine if calibrated properly and calibration is maintained.

Edit: This thread needs this link and should be read.

Refractometers And Salinity Measurement
http://www.reefedition.com/refractometers-salinity-measurement/