[unclejed]

To respond to pog, blanket statements on any subject are usually bias toward what the speaker believes. If you use a hob filter or canister than maybe gas exchange is hindered "somewhat". If you have good surface agitation however, maybe not. If you employ a sump, then you get all the gas exchange you need not to mention if you have a skimmer. I have always used glass tops with no ill effects what so ever. As far as light rays being diminished, that to is a misnomer as far as the glass having any real overall "bad" effects. How high are the lights above the tank? What type of lighting? Is the glass non-reflective? All these have a bearing and from my research into this very subject, the diminished effect glass has on the light is minimal. Your water itself has a far greater effect on how much penetration you are getting, thus, proper intensity is now the idea instead of watts per gallon.