How often do you calibrate your refractormeter??

[Nicole.]

I never calibrated mine since the day I first got it which was prob a couple years ago...big mistake. Just recently had a buddy test my water and it was at 1.022 even though it would show as 1.025 on my refractometer. Who knows how long it's been at 1.022??! I've had a bunch of nice corals die and gave up on them because I couldn't figure out why at that time... Now I will calibrate mine after a couple uses. A bottle of proper calibration solution is only $5 so it's worth it.