Everything I've read says the Milwaukee digital refractometer is the most reliable instrument they own for testing salinity, so I trusted mine for months. But then I started getting suspicious. New batches of saltwater (50g bag in 50g of water) were testing low. LFS water that my fish came with tested low. Then I picked up a frag and a fish from two different people in my local club and the water from each guy's tank gave the same low reading of 1.018 SG. Ca and Mg were testing really high (but not Alk), even after water changes. I found an old glass hydrometer, which I've always mistrusted because I figure the paper can move, but it gave a much higher reading than the Milwaukee. I checked and re-checked the procedures I was using with the Milwaukee, cleaning off the well with RO/DI water, calibrating with distilled water, letting the temp adjust, etc.
Well, I just got a new BRS refractometer with test solution and sure enough, I have been running my tank at a salinity of 48 for the past 3 months. The weird thing is that things seem ok. Fish are thriving. My cardinalfish mated and produced eggs (but I think aborted). Fish are eating and growing. Corals are doing ok. Not the best coloration or fast growth, but it's only been a few weeks. Is it possible that running really high salinity is not bad for a reef tank?
Obviously I want to lower it. I guess I can do daily water changes with very low or no salinity water. How slow should I go? 1 PSU/day? I can do the math to figure out how much to change every day at what salinity to achieve this, but is there a calculator?
Well, I just got a new BRS refractometer with test solution and sure enough, I have been running my tank at a salinity of 48 for the past 3 months. The weird thing is that things seem ok. Fish are thriving. My cardinalfish mated and produced eggs (but I think aborted). Fish are eating and growing. Corals are doing ok. Not the best coloration or fast growth, but it's only been a few weeks. Is it possible that running really high salinity is not bad for a reef tank?
Obviously I want to lower it. I guess I can do daily water changes with very low or no salinity water. How slow should I go? 1 PSU/day? I can do the math to figure out how much to change every day at what salinity to achieve this, but is there a calculator?