escape proof hoods
Will there be any weight put on it?
I have 1/4″ on my 48″ tank but I do have a middle support so it’s two 18″ by 24″ panels. Why don’t you have a middle support? Does your front and/or back glass bow out? I’ve seen them bow even on 48″ glass tanks where the middle support had been removed or broken.
Except for the “Rimless Tanks” (really thick glass), all of the 6′ glass tanks at GlassCages.com have two braces for the ones they have pictures associated with the tank. http://www.glasscages.com/?sAction=ViewCat&lCatID=2
Is your front to back 18″ or ???
If it’s 72″ x 18″, you would probably need the 1/4″ to minimize the sag in the middle… if you do not put stuff on it. If you do store light weight stuff (fish food containers, dechlor, etc… like me) on top of your cover, then you might want to first create a middle brace out of a piece of the plexiglass first just to keep it from sagging too much. A little sag is OK as it allows the evaporated water to condensate and then drip back into the tank faster… instead of just hanging around as drops on the plexiglass.
Another thing you can do is drill a small finger hole in the panel(s) for lifting them and also for feeding the fish through the holes. 
A corner cut out also works although a slithery fish or snail trying to escape would be more likely to find that corner cut out.
Lenny Vasbinder Fish Blog - http://GoldLenny.blogspot.com (Links to any articles referenced in above reply are listed on the right side, alphabetically under Labels and also under Archives by Year, Month)
Category: Philippines Internet Koi Society
