Glass Tank Covers and Effect on Lighting

Hello All,

I have a 55 gal reef tank with most soft corals, leathers etc that is doing very well. The lighting is a 48" 4x96W compact fluorescent hood. In my LFS I see that most of the tanks are not covered, with the light directly over open water. My tank is currently covered with two Plexiglas panels. I did this to help cut down on salt spray and evaporation. I am wondering how much effective light is lost with this cover and should I be using one at all. I am currently getting ready to upgrade to a 90 gal with MH lighting so the timing is right for this question.

Thanks,
Mark

 

One reason for not having the tops on is for better gas exchange in the water.
It's also a lot of work to keep the tops clean from saltcreep and stuff. as far as how much light is lost I'm not sure.

 

depends on the thickness and type of acrylic. Either way I recommend getting rid of it. As horton says, gas exchanged. And also light is lost. When you get the MH you will NEED the evaporation to keep the temp in the tank down, unless you have a nice chiller.

 

I agree with the above two responses. I also must say I bought a tank once that came with plexiglass panels instead of glass tops and the eventually started to bow from the heat from the lights. I no longer use any tops on my tanks. Because of the lack of gas exchange my pH was getting very low. Not to mention the light blocked from the glass.

 

I have glass tops. Other than keeping them clean (salt creep), I don't notice a big difference light-wise. My sump is open, and IMO that does the job of gas exchange.

 

With the metal halide coming, I would get rid of the covers. They trap the heat in for sure.

 

bbsbliss, you won't notice anything visibly to the eye as far as light. But par values do drop...

 

True, but at the moment I'm not keeping any corals with high light demands. As with everything, I base my comments on how my residents look and act- if it looks happy, I leave it alone!

 

Hi Mark, here is a very informative article about what you are interested in; Re: glass over tank when using hood? (A treatise on HO T8 shoplights & d Many aquarists believe glass distorts and diminishes the par and/or Lux values but this will show how minuscule that really is and goes on further to show other more proportional ways light is "lost".
As far as gas exchange, any skimmer worth paying for does that for you. The only other consideration as mentioned is heat which may or may not be a problem.

 

thanks everyone for the great responses