Accuracy of Refractometer - Scale Reading

[Cedric]

Hi to all,

I happen to have with me the two refractometers from Reef depot and a third different one I got from a fellow reefer direct from US.

Out of curiosity, I calibrated all three with ultrapure grade water I got from a lab and proceeded to take reading of my tank water using all three refractometers.

The reading I got was quite surprising. All three showned 35ppt but the similarity stops there.

Mine shows 1.026SG but the two from Reef Depot showed 1.027SG. Which means to say the scale is different!

Does anybody now of the actual concersion to convert 35ppt to SG?

[Achilles Tang]

There should be different grades of refractometers.

Not surprisingly, the accuracy may differ.

[Cedric]

Found this Conversation, might be helpful! Hence I recommend using the ppt scale as it seems most consistant according to my little experiment.