Deciding to cover your tank or not is not an easy decision. Here are the arguments for and against having a cover. If you choose to have a cover, you’ll then have the choice of a glass lid, a screen, or a wood canopy. Open Top Open top aquariums are growing in popularity—especially since rimless aquariums have become more widely available. Here are the pros and cons for having an open top Pros Easy entry for maintenance No lid to clean Plenty of evaporative cooling Plenty of gas exchange Excellent to down viewing Allows for fun aquascapes with plants or decorations coming out of the water. Cons No protection against jumping fish Increased evaporation Increased room humidity Poor heat retention Glass Lids Glass lids are the most common kind of aquarium lid. Most glass lids will sit inside a shelf built into an aquarium rim and have a hinge in the middle, as well as a cut away portion in the back of the lid for routing equipment wires and hoses. Pros Reduced evaporation Reduced home humidity Protection for jumping fish Excellent heat retention Cons Difficult to enter the aquarium Extremely difficult to clean Reduced light penetration Low gas exchange Poor evaporative cooling Screen Lids Screen lids have become more popular as aquarists search for a way of preventing jumping fish while reducing the headaches that come from glass lids. Screen lids are usually a DIY project using window screen. Pros Protection for jumping fish Plenty of gas exchange Plenty evaporative cooling Cons Difficult to enter Some minimal maintenance Un- attractive looking Increased evaporation Increased room humidity Poor heat retention Reduced light penetration (not as extreme as with glass.) Wood Canopies Wood Canopies were once very popular, but they now are only seen on large professionally installed aquariums. Wood canopies do not cover the surface of the aquarium but instead they form a wood shell around the top off the aquarium. This design can be used in conjunction with screen or glass lids or without. Pros Moderately easy for maintenance No lid or screen to clean No light spill into the room Plenty of gas exchange Plenty of evaporative cooling Good protection against most jumping fish Matches home furniture Hides all lighting and equipment above the aquarium Cons Expensive Increased evaporation Increased room humidity Poor heat retention Some extra difficulty entering the aquarium. No top down view