A well planned refuge can mostly take care of all your needs. The problem with most manufactured sump/refuge designs is 1:the refuge section is not large enough, and 2:the flow is too fast as it is coming from your tank return pump. If you can get the volume of refuge to about 10% of your tank volume and get the flow down to 250/300gph, you'll get great results.
Carbon dosing is another option, but that's down the line, and I can't remember why, but I do remember it's a good idea to wait for the tank to get a bit mature. I'm currently running nopox on my 90g Pred, currently 3 lions and a filefish, but has housed 3 lions and a ribbon eel, and 4 lions.
Target feeding eels and lions appropriate size foods will cut down on mess. If you cut the eel's food into chunks or slivers he can get down without ripping and shaking, it cuts the mess dramatically. Nassarius snails are great to eat left over food, they bury themselves in the sand and only come out when they smell food. So pretty safe since they will only be oiut when you are feeding the eel, so the eel will be eating your food, not the snails. Not so bad to add a dozen hermits from time to time, if the eels hunt them, well good for them. Lions won;t bother hard bodied inverts, but shrimp are yummy.
Check out some of my threads on lions and predator care and feeding.