filtertration in sump

Hello,
I have this aquarium running:

30 gallon oceanic
2 T5 lights
2 LED lights (4 watts each)
some blue
RS175 sump with filter sock and sponge between chambers
CoralLife 65 ProteinSkimmer
10 pounds life rock (taken from other aqarium)
40 pounds live sand (black and white)
20 pounds of live sand in sump (taken from other aquarium)
hang on back overflow for 100gallon tank
powerhead for 50 gallon aquarium

I'm looking at getting more live rock, and drilling holes in it, and connecting it, maybe with pieces of plastic clothes hanger or something like that, since it's really tall. there is a local fish store that has cured live rock, with nothing on it which I plan to use - it looks purple.

A couple questions:

the water isn't crystal clear, and I presume I can have it be clear with mechanical filtration. I was thinking of getting a hang on back filter with carbon in it, or some type of filter like carbon. then I realized maybe I don't have to buy that since the water all flows between two chambers, and there is a sponge there, can't I just put carbon there? then the water should be crystal clear?

the protein skimmer is producting a little in wet skimming mode. the bubbles go to the top, and micro bubbles set about 3 inches up the chambers. does it just have nothing to skim, how can I get it to do dry skimming?

Thanks

 

There are some pretty cool AquaClear HOB mods from inTank.
Hagen AquaClear

Very nice setup btw, that is a pretty large skimmer!