Which Refractometer Is Wrong??

[nabee24]

I had my aquarium evaluated and the guy used his refractometer and found that my SG was 1.030! Then we used my refractometer and got 1.025. Today, I borrowed my friends' and got 1.018! All refractometers were calibrated with ro/di water, at 1.000. I don't have a needle pin tester. How do I know which ones correct? I would like to avoid purchasing another $30-60 refractometer if I could. Current one if from marine depot.

Thanks!

 

[eggiel]

Nabee there is two things you could do purchase pinpoit solution 53.0ms and veryfie with that as water is not the best to test with
or
do a search in the Reef Keeper web page and look for salinity home made solution from randy holmes i did like he explains and it gave me a good reading of 1.026
I use both and they are pretty good

 

[sjm817]

Dont calibrate @ 1.000. You want to calibrate at the range you are testing for which is 1.026/35ppt. Get some Pinpoint 53ms calibration fluid and calibrate for 35ppt.