I clean mine thoroughly every other month or so. You will notice that the output decreases as they get dirtier.
, 65 lbs Fiji LR
, 4" Aragamax DSB
, Coralife 2X96w CF
, CPR Bakpak II, CPR Aquafuge 12 w/ 2x9 Coralife Mini Aqualight, 4 Maxijet 600's, PCI 200W Titanium Heater, 2 Blue Green Chromis, 1 Gold Bar Maroon Clown, 1 Purple-Stripe Dottyback, Finger Leather, Trumpets, Rose Coral Open-Brain, Pagoda Cup, Xenia, Star Polyps, Yellow Polyps, Various Mushrooms, Toadstool Leather, 12 Astraea, 10 Nassarius, 4 Bumble Bee, 6 Cerith Snails, 12 Red Tip Hermits.