Everyone cross your fingers!!!
The problem of using Prime with no ammonia is that it consumes massive amounts of O2. So now you have bacteria going crazy (clouding the water) that are consuming lots and lots of O2 and you just added Prime which will lower O2 even more. This is why I suggested not adding it unless you actually have a problem with ammonia.
On both they look kinda disenegrated. Not totally but enough to make them look really bad. Crabs are ok and the snails seem to be ok as well.O2 deprivation?
Total guess. If snails and other bottom dwellers are OK then I have no idea why starfish would die.
Did they just stop moving or did they start to disintegrate (could be osmotic shock).
Look through the eyepiece again and look at the other side of the scale. One side will list "d 20 20" or something like that. That scale is not an accurate reading of Specific Gravity since refractometers do not measure S.G. Ignore that side.
The other side will list something like "0/00". That is the Salinity side of the scale. On calibrated ATC refractometers this salinity reading will be highly accurate.
Yeah, sometime back in the early 80's people stopped deriving the actual salinity and settled for knowing the S.G. only. To derive Salinity from the S.G. you also need to know the temperature of the water and a conversion chart. This is why the S.G. on a refractometer is not accurate, it will automatically cool the water to room temp for the reading. The salinity is still accurate since salinity is not affected much by temperature. It actually got to the point where people were getting very accurate Salinity readings from conductivity meters and going through the trouble of converting to S.G. ????I'm glad I'm not the only one.