You can skim amazing amounts out of the common tank. Key is to remove bio toxin and contaminates but trace elements can also get skimmed out too. You get a feel for your tank after a while. It becomes like sonar and you can tell by looking that the inhabitants arent happy.
If they ARE happy then dont let the amount of skimate dictate what defines a good skimmer from a poor one. if you rlooking to remove particulate perhaps a bit of carbon or a filtersock for a few hours once every few weeks. This should give you the crystal clear look without losing the important things.
JMO but remeber I also run a seaclone, so go figure