I've had my refractometer for about 14 years. I haven't used it in a while (I don't have a tank presently) but it holds a calibration really well. This is the devise I used in the store every day for over 11 years. I'd check its calibration from time to time but rarely ever had to adjust it.
It's not a fancy one either - I paid $25 for it in one of the very first group buys with ARC back in like, 2001 or so. Back then RO/DI was the only calibration most people used, and the Pinpoint stuff wasn't widely available.
As knowledge and technology moved forward, I started using the Pinpoint stuff and there is a slight difference than calibrating with RO/DI - mainly, with the solution, you are calibrating in the range you will be measuring, versus 'zero'.
The biggest 'cause of death' I have seen for refractometers is storing them damp, in the box they come in, and in the aquarium cabinet that is also warm and humid. The metal pin that holds the little plastic cover down on the lens, rusts and either breaks, or prevents that cover from closing properly, which will skew the reading at worst, or make it really difficult to see a reading, at best.
I got rid of half of the box, and stored the device on the counter in the open air, in half of the box with the foam insert, so it wouldn't get jostled around. I used the same device on the road doing services, and made sure to unpack it promptly when I returned it to the shop.
My service tech, was rougher on her refractometers and she'd get about 6 months out of one before it died/broke/wouldn't hold a calibration.
IMO the Pinpoint solution works fine, but if you feel better with something else, go for it. I just think how you handle and care for the actual device, has a big impact on your results.
Jenn
