on amazon they sell calibration fluid with TDS of 342 PPM. if yours reads 350 with the controll of 342, then just subtract 8 during a normal reading if you cannot calibrate the machine.
I have a different question. I heard the rodi units can go bad after sitting is this true and how long of a sit does it take? If its brand new and dry can it sit for a few months? What about wet? So excited to find a drilled tank now!
I have never owned saltwater setup. I have been addictively reading up on reef/fish keeping. Im looking to buy an aquarium. Need reccomendations on size. I am considering a 125g and would like top of the line equipment. I would also like to buy a book on reefkeeping. thanks