Hi I just put a cf lighting system on my 29 gallon tank I am wondering if I should leave the glass cover on the tank or should I take it off does anyone know if this will affect the light getting into the tank or does it not really matter?

it WILL lower the lighting in the tank. it will also make gas exchange more difficult unless you have a sump with a large surface area for the gas exchange to take place. i would say NOT to cover it, just be careful and research the fish that you decide to add, to keep them from jumping.

even with metal halides ... a cover makes lighting far less affective.

I agree with everything Bobby said and just wanted to add that leaving it uncovered will speed up the rate of evaporation and could lead to significant swings in the Spg. If you elect to leave the glass top off you will want to closely monitor it and/or add an ATO in order to stabilize the SpG.

If you do decide to keep the glass canopy, try wiping it down every few days with vinager.

The only time I'd cover, is if you have an eel or some kind of "Houdini" fish that can slither out. Even at that, a good egg-crate/diffuser cover will keep jumping fish in.

Evaporation rate is not a bad thing, per se. It does help cool off the system. But, as mentioned, you'd need to be religious in your top off routine.

Dave

I'm not a big fan of covers either, but i do have a single pane of glass over my 12 gallon nano. i have a coralife 150w HQI light over it, and the UV shield is inadequite on it, so i have to use an aditional piece of glass. It's a real pain, and I'd really rather not have it, but it's a necessity. I have to rinse it off every few days, it traps more heat and it definitely reduces light, even when it's freshly cleaned. IMO, especialy with a CF fixture, you're going to want all the light you can get.

Yes... yet another reason... MOST glass covers (unless rated for intense light passage) filters out 95% of UV lighting. Good if you want to protect yourself in the car, bad if you want these spectrums to reach your corals. :)

Dave