If you can afford a new one I would go that route so you can be assured it is correct & get some calibration fluid as well. Talk to the crew at Concepts, Im sure they can fix you up.
+1. Plus the big day is coming and concept will be throwing crazy deals. I am pretty sure that reading is at least 0.06 off. And don't be too lazy, mix your own saltwater
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You wouldn't want to see my tank. I don't use fancy equipment and I am a noob