This is ONLY my opinion...I am no expert, so if somebody thinks the info to be wrong pipe in.
In the middle of the week do a 15% water change, It will be fine. Some people don't even own skimmers (tank size ?), I don't think it wise but it won't kill anything. The only reason I think for the water change is to keep the tank looking pristine and to be absolutely sure everything is okay.
The stuff skimmers pull out can't be tested for. So doing tests won't tell you if particles of micro whatever’s are there or not.