I tried keeping jellyfish for about a year then gave up. There’s really not many additional things you can do to the tanks. I tried moon jellies and blue cannonballs. They are so delicate and fragile that even cleaning the tank can damage them. All I can recommend is constant monitoring dedicated water changes. Feeding freshly hatched baby brine shrimp makes a difference (less waste on the bottom) but be warned. It’s a lot t of work and for what they cost, they don’t live long. Gotta admit tho, I loved just sitting and watching them in the evening. It was very relaxing and they are cool. Good luckI was given a jellyfish tank as a gift that looks like this (though this isn't the actual brand I have).
It's about 5 gallons and I'm having trouble deciding on a reliable ATO for it, not to mention the tank's circular shape may be a challenge for putting in an ATO...