Couldn't answer accurately:
- I skim on a 'need to skim' basis and use water changes. So, had to vote never
-I use ChemiPure which...is...? resin/carbon? had to vote no
-voted on sump on the last, but, might have been a good choice to add 'refugium'.
I empty the skimmer collection but it runs to a large gallon jug so it takes about a month to fill up. When I empty the jug I also clean the cup and neck.
I don't use any carbon unless I am trying to remove chemicals out of the tank.
I use a combined 35-50 gallons in my sump and refugium.