Hello all, this is my very first saltwater tank that has one blue blubber jellyfish in it. It's in a 3.0 gallon aquarium with filtration, lighting system, etc (Marineland kit). This is my second jellyfish, as I accidentally killed the first one after one week--not sure how, but I suspect I underfed it (I was feeding it 1/4 cap of reef zooplankton twice a week per instructions from pet store employee). That first jellyfish was in tank water from its original tank. When it died, I didn't change the water. The new one was from the same tank at the pet store and I was given extra water from its original tank to help acclimate it so I took out about half the water from the last batch and added the new water and jelly. It's been 24 hours and it's floundering around on the bottom of the tank, bell down. I read somewhere this is due to the salinity of the water (but if anyone has any other ideas, PLEASE let me know). I added some saltwater (pre-mixed from pet store, allegedly from Catalina), and the jelly seemed to perk up for a few hours, but now he's back to floating around the bottom of the tank. Bought a hydrometer to check salinity, and the reading is off the charts, which can't be correct seeing as how most of the water is from the pet store's tank. Not sure what to do to get the little guy to perk up. Any help is appreciated! Thank you!!