Hanna meter has been verified against another meter a while back but I'll check it again.
All my SPS are SLOWLY dieing. I feed pellets, frozen mysis, frozen brine, reef chili, liquid coral food (Red Sea) 2 out of 3 days. Just started with the coral foods though. Every 3rd day the tank doesn't get fed while I'm at work.
50g display, 40g frag tank connected to a shared 10g water volume sump. 3 total tangs, 3 clowns, royal grama , long nose hawk, 2 damsels