Tank Coverings?
 

What plastic/acrylic/plexi passes the most light& U.V.? Anyone know which type is best suited for a tank cover? Were losing water like crazy, didn't really wanna do it but mabey it'll help!:idea:

I can appreciate wanting to cover your tank for this reason but be sure to consider some ramifications. For one, covering your tank with anything non porous will trap heat and will likely cause your tank water to increase in temperature. The act of evapouration helps to cool down the tank. Secondly, depending on how high your water level is, a tank cover can tend to develop salt creep over time as water splashes onto your cover. This will reduce light transmission from your light. You will find yourself having to clean the cover often if this happens. Anyway, these may be non-issues for you but something to think about just in case :biggrin:

Also, there is the possible loss of Oxygen exchange with a top. More prevalent in SW tanks than FW as SW doesn't hold oxygen as well as FW.

That said, there are a lot of successfull covered tanks. Plexi is probiballly going to be the cheapest and clearest. I had 4mm glass covering one of my tanks once, and was forever cleaning it. You could see the light difference even with clean glass. Now, I just live with the evaporation. try keep tank a touch cooler? room a little warmer. That will lessen evap too

iv seen black eggcrate, may not help alot but might a lil?

I highly recommend that you do not cover your tank with anything, unless is fine mesh to control jumping fish.

CO2 gas builds inside your tank all the time, and if it doesn't have a way to get out, it will lower your pH... which can be catastrophic. You need an open top so that the gases can exchange (ie CO2 for O2).

The most transparent material to most wavelengths of light and UV is quartz. You can get quartz glass for not much more that regular glass. POlycarbonate and acrylic absorb UV and can begin to yellow with time. However, I must echo the comments above about covering your tank. If you are loosing water like crazy it would be WAAAAAAAAY cheap building yourself an ATO. You could build one for about $20 to $100 depending on how resourceful and crafty you are.

Don't mean to hijack Sleschwin but any info on building one of these Steve?

Yup, tons of info on DIY ATOs.

http://www.autotopoff.com/
http://www.melevsreef.com/plumbing/auto_topoff.html

Use the ol' Googletron to find a lot more. For the love god, please be careful when using line voltages when you if you want to make one. And remember: You + Aquarium/Water + Electricity = Extra Crispy.

If you have a skimmer, it should be more than enough for oxygen exchange. One pass of water through the skimmer has more gas exchange than you will ever get through the open top of your tank.
However it doesn't address the evaporation/cooling advantage so it depends on your tank. If you have T5 or VHO or even 150de hqi over your tank, i wouldn't be too concern about keeping the tank cool. But I found a big difference when I went up to 250W dehqi bulbs that it heated up my tank considerably.

Empty your mail box there sleschwin ;