[justinl]

make sure they are casseiopeia. After that it's really quite simple (as far as jellies go) to keep them. The nice thing is that they do not need the very expensive semi circle or circular kreisel tanks because they stay on the floor. only pelagic jellies really need kreisels. a standard tank will do fine.

Then think about their natural habitat: lagoon, various salinities (but constant). Which means put them in whatever salinity you buy them in. They can be anything from brackish to full salt. not sure about hypersaline. VERY low flow. any intakes must be sponge covered or something to keep from sucking up the jelly. high light (halides) since they are mainly photosynthetic. Should accept a range of fleshy marine foods as well.

edit: fine sand bed is important too. something like crushed coral is way too abrasive for something that is nothing more than a sac of water in a thin membrane.