here's a handy tip: to keep your hood glass clean from dust, insects, slip an air filter over the intake end of the hood ... WalMart, Home Depot, etc., sell a round air-filter to fit their shop vacuums ... it fits a 6" duct perfectly, its about 8-10" in diameter, has a rubber lip around its edge, that holds itself in position, usually not even needing a clamp ... cheap, too, I think I paid about $10 for mine ... never seems to need replacing, because grow cabinets are clean (or, should be ) ...