I picked up an adhi 60 sump, it has a first chamber, 2nd chamber could be used as a refugium or something else, filter pad and then the 3rd chamber. I have my mr-2 in the first chamber which is pretty tight. Should I have the return of the sump dump back into the first chamber or into the 2nd chamber? I might have a refugium, i might not not really sure, might just use it to keep a bunch of frags down there. Im also using a submersible for the skimmer feed, what chamber should I place that in?