Make sure you put the cap back on the calibration fluid really tight cause water will evaporate just as it does in our tanks leaving salt behind, that's the reason why calibration fluid slowly creeps up. I replace mine every few months. It's better to spend a few (probably unnecessary) dollars than risking not only the money invested in the tank but most importantly the lives of the creatures that we took from the ocean.
Just my opinion.
Just my opinion.
