380g plywood tank help

[matty.green]

Hey guys, new to this site and about to start building my 1st plywood tank. Got most my materials ready but just have a few niggling questions I was hoping u guys could help me with. 1st is about glass thickness, my tank is gonna be 72x36x34high. The glass will be 64x24. The bottom of the glass will be 4" from bottom of tank and top will be 28" from the bottom. Anyone know what thickness I'll need?
Secondly I'm gonna coat the tank with epoxy fibreglass Matt. Will I be able to silicone seams inside before I fibreglass it or not or is there no point in doing that at all. Any help at all as I'm hoping to start on this tommorow. Thanks guys

 

[matty.green]

Someone help please

 

[Drstrangelove]

Hey guys, new to this site and about to start building my 1st plywood tank. Got most my materials ready but just have a few niggling questions I was hoping u guys could help me with. 1st is about glass thickness, my tank is gonna be 72x36x34high. The glass will be 64x24. The bottom of the glass will be 4" from bottom of tank and top will be 28" from the bottom. Anyone know what thickness I'll need?

I'm going to assume the water level will be up to 33 inches above the bottom, giving you 1 inch open space at the top of a 34" tall tank. If this is wrong please post the correct number.

At that depth the glass (float or plate glass) will need to be 17mm to gain a 3.8 safety factor. At 15mm, you will get a 3.0 safety factor, so if the glass is new and made by a reputable source, 15mm might be fine. Make sure to give decent bracing and that should work.

Please note that it's the depth below the water level that directly impacts the glass thickness and that water above the glass that is behind the plywood is increasing the thickness. If you drop the tank to 28" tall with the glass 4" from the bottom, the glass thickness will need to be only 13mm (3.8 safety factor) or 11mm (3.0 safety factor.)