I use a paper towel soaked in hot water in one hand and follow that with a dry paper towel, using circular motions. Then I go over it again with the dry (now slightly damp) paper towel and 'buff out' the whitish residue.
FYI, I use Sellar's Rags from Lowe's. They're $10/box (200 ct) but they're the best disposable shop towels. Scott's "Rags-in-a-Box" used to be, but they switched to a different style of rags which now sucks, so don't get that. Sellar's brand is just like their old version.
My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication