the update seems to imply things are better though. I wonder how much of the issues with the jellyfish tank was people just not being capable of maintenance. also, if your jellyfish keep getting stuck on the rocks... remove the rocks, remove some of them?
It's a common misconception that betta thrive in those environments. unfortunately a lot of them survive living like that. we just know better
You can't have rocks in a circular jellyfish tank, as far as I am aware. The jellies need a circular current and a round area so they won't be trapped or stuck. Take the rocks out and that tank- provided that it has a slow circular currant, should be fine.