My opinion is that if you are going to do corals then you will end up adding a sump. They are great! Not only does it add water volume which is nice, but it also allows you to hide all your equipment. If you can't add one look at the Coralife super skimmer. It is possible to hang on the back and works much better. Just be very careful especially the first week or two as they have a tendency to overflow every once and awhile. As for the Filter, I am not sure but I would say at least weekly. There is a reason that most reefers don't use them.