Acrylic work

[jackri]

I'm planning on making a frag tank.. oh about 4 foot x 3 foot by 12 inches high with a 30 gallon sump (similar to one I've already made) all out of acrylic.
Just called on prices locally... I can have it cut to size in 1/4 inch for 5.50 a square foot or 9.00 a square foot for 3/8 inch.
Using 3/8" on the main frag tank part just the bottom alone (being 12 square feet) would run over 100 bucks.
Anyone made a tank this large out of acrylic using 1/4"? It's only going to be 12 inches deep so there wouldnt be a lot of pressure but at the same time I don't want to bust a seam. I'd run supports along the top edge as well.
The sump I made is made from 1/4" and holds 16 inches of water and 26 gallons total volume with no leaks. Thinking the frag tank will be closer to 90 and I do want to build to MY SPECS instead of buying a used tank.
Price isn't a huge issue... but why spend more than I have to? Still have the skimmer, heater, Halide(s), pumps etc to get and I don't really want to go over the 1,000 dollar mark too bad

This is just pre planning, I still have to run electricity to the room (storage room roughed in for a bathroom but I already have 2 bathrooms and only 1 saltwater tank hehe) and build a stand which I might start doing shortly.

 

[scsinet]

So the bottom is 4x3 and iso that's $108? And you're complaining?
Yeesh. 3/8 cell cast where I come from is about $450 for a 4x8 foot sheet.
You kids today don't know how good you've got it!

Anyhoo, if you are planning to support the tank evenly across the bottom by placing it on a foam underlayment, then I'd say you can use 1/4" on the bottom with no problem.
As for the sides, 3/8" is what I'd use. Over the length you are talking about, even with heavy eurobracing you are gonna have some bow to contend with if you used 1/4". The eurobracing can probably also be 1/4". Even with 3/8", I wouldn't skip the bracing. I figure you'll need about 14 ft2 for the sides.
Don't forget when you are having the sides cut that they will have to be cut shorter to compensate for the butt joints at the end. So if your acrylic is 3/8, you'll need 12" x 47.625" and 35.625" for the 4' and 3' pieces, respectively. That, or have your bottom cut to 48.75 x 36.75". Of course if you've done this before I'm sure you already know that.

 

[acrylic51]

You could probably get away with using 1/4" for the bottom, but IMHO I'd opt for 3/8" the whole way around. 3/8" would be plenty for this.