Originally Posted by CleverBs
ok so it promotes the gas exchange, but it still does it with a lid...maybe not as much but by adding a lid I find it hard to belive that there is no longer a gas exchange between the water and the air, as long as the lid isnt air tight I dont see how this would become an issue or even hinder the gas exchange that is taking place on a microscopic level. Im not arguing that it doesnt im just saying with the amount of information you are providing is inadequit to decide if the lid is a good or bad thing. my questions are what effects will having a lid have on the water chemistry based on this gas exchange, what are your reasons for knowing this is an issue? If it is why do majority of people have a lid? Finaly alot of the time LIDS are maditory anyways to prevent fish from jumping out of the tank beings alot of marine fish will based off the information I have read.
Glass lids with all the plastic edges that completely cover the top of the aquarium do interfer with gas exchange on saltwater tanks. The effect on water is a resulting drop in pH. While not a huge issue, it does occur. Additionally, on tanks that are predrilled, the lower water level allows the accumulation of saltcreep on the lid, inhibiting light from reaching the corals (this in my opinion is a much bigger issue than the gas exchange). Can't speak to this particular forum, but the majority of people on the other saltwater forums I frequent do not have glass lids. In fact, most don't use any type of lid. However, those who keep fish, like firefish which are known jumpers use a mesh cover to prevent the fish from jumping.