I'm putting together a rimless tank (39" x 12" x 12") and will probably add a lid to it. Being such an odd size, I know I need to do a DIY lid. Nearly everyone I've seen online makes lids from either glass, polycarbonate or acrylic and then hang them inside the aquarium with clips, so the lid sits down and inside the inner edges of the tank. My question is, why does no one sit the lid directly on top of the top edge of the aquarium? Seems to me it would be more secure sitting on the top edge rather than clips and would square up the look with the edges of the tank nicely (obviously would have cutouts for filter, tubing etc.). But is there a reason why I shouldn't just sit the lid directly on the aquarium edges rather than using clips? Will evaporation seep under it and run down the sides of the glass?
Also, I see online some people drill a few large holes or dozens of small ones for air circulation under the lid (usually in acrylic), and others don't. Assuming the lid has a few cutouts for filter, tubing, heater cord, etc. and is not completely air tight, would you still recommend adding a few large holes or several smaller ones for air circulation? Seems like that might defeat the purpose of trying to eliminate evaporation by giving water more holes to escape from?
Also, I see online some people drill a few large holes or dozens of small ones for air circulation under the lid (usually in acrylic), and others don't. Assuming the lid has a few cutouts for filter, tubing, heater cord, etc. and is not completely air tight, would you still recommend adding a few large holes or several smaller ones for air circulation? Seems like that might defeat the purpose of trying to eliminate evaporation by giving water more holes to escape from?