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.
