losing water due to filtration

[_Jessica_]

3" or so for both my 55g. I've heard glass tops are really helpful with evaporation...but I just have plastic lids.

 

[SteveR]

Its not a big deal but im just wondering if anyone else loses a lot of water due to evaporation? I lose about 3 inches every week of water in my 29g. My tank is in my basement and therefore the air is very dry. I just refill it everyweek and according to water changes........this happen to anyone else?

Too much evap if you have a lid...How big is that opening in the lid?