i had the exact same problem, my swing arm's weight had fallen out and it kept showing my salinity way too high, as high as the arm could go so naturally i would keep adding water until it would go down and it woulnt so of course i got someone over here and i had raised my salitity WAY to low, as low as it could go around .013 or something like that and everything managed to survive i think but right after that i got into a major kick of checking every parameter of my tank and started doing the pH thing and got a hold of a broken one that registered it 1 whole point too high to like 9 so i was dumping vinegar in the tank in fear that everything in my tank would die, and in fact the pH thing was broken and i wound up killing everthing but a couple of crabs in my tank, i lost my perc clown, yellow tang, and my striped damsel which was my first fish...not a good experiece!