Low Salinity??

[Reef_surfer]

i use a coralife hydrometer and i havent had a chance to use a refractometer... but i make sure all the bubbles are out of the hydrometer when im testing

[Doug]

Perhaps have your hydrometer checked by someone with a refractometer. If its not being skimmer out then the salinity should not drop that much, unless replaced by fresh water somehow.