16 to 20 mm glass price

[KevinK]

douse any one have some indication of glass prices in the 16 to 20 mm ?

also where would be the best place to get it.

thinking of building a large plywood tank (400 to max 600 gal), and to be safe, I dont want to get into 12 mm

pannels need to be max 5.5 feet, x 36, but the minimum would be 4.5 x 30 inches

I would need 2 pannels