Large plywood tank

[P-Dub]

I have to admit for some reason when i here people on here say Marine plywood My mind has a image of Treated Ground contact ply .Something i use occasionally for exterior projects . Not Actual Marine grade Finish plywood Something this is Generally not available in this area. I know they are Completely Different animals .
I do as well feel this is a much better place to discuss a topic then others.

That would be any "pressure treated" lumber products. Yes, completely different animals. The only similarities between the two are they are both a cellulose.

 

[paphater]

Marine grade is better but is not required. Many people successfully use plywood straight from the big box store.

 

[That Crusso Kid]

Not sure what you mean by cleating and bulkhead but I will be using reinforced euro-bracing.

Also, I am going to use Pond Shield by Pond Armor for sealing the entire thing with fiberglass reinforced seams. As for the inserts, nothing fancy, just silicone.

You will have to reinforce a length you are planning on. Some sort of cleating and bulkhead. It may not have to be a solid, one-piece bulkhead but you will need cross-sectional reinforcement or it will bow and stress your seams.

 

[That Crusso Kid]

For smaller aquariums, I'm fairly sure the big box store plywood is fine. There is not that much pressure to cause a void to fail. Much more gallonage means much more pressure causing much more stress on weak points aka voids in plywood.

Marine grade is better but is not required. Many people successfully use plywood straight from the big box store.

 

[dantimdad]

I have to admit for some reason when i here people on here say Marine plywood My mind has a image of Treated Ground contact ply .Something i use occasionally for exterior projects . Not Actual Marine grade Finish plywood Something this is Generally not available in this area. I know they are Completely Different animals .
I do as well feel this is a much better place to discuss a topic then others.

Same here. What is sold around here is what you are describing and I would NEVER use it for a tank.

I have built many over the years. I found out a few years back that 14 of them I built for one lady were still in use from 1994!

I used A-C back then but can't find it anymore. I will use Russian Birch if I do it again. It's not the same as Baltic birch from my supplier. It's 4x8 13 ply. Really good stuff.

 

[P-Dub]

Not sure what you mean by cleating and bulkhead but I will be using reinforced euro-bracing.

Also, I am going to use Pond Shield by Pond Armor for sealing the entire thing with fiberglass reinforced seams. As for the inserts, nothing fancy, just silicone.

A bulkhead would be something like the first photo below. A cleat would be similar but a much-abbreviated version of a bulkhead as in the second photo.

Think of cleating as the bulkhead with about 60% of the body removed.

 

[paphater]

For smaller aquariums, I'm fairly sure the big box store plywood is fine. There is not that much pressure to cause a void to fail. Much more gallonage means much more pressure causing much more stress on weak points aka voids in plywood.

Most of the larger tanks use fiberglass so the glass is the primary structural unit. It's also common to use extensive ribbing with dimensional lumber. Like I said I agree that marine is a better material but now days, especially large builds, any weakness in plywood is usually mitigated with proper building.

 

[Shooter6]

Alexg on here built 2 very large tanks from plywood. Youtube has many plywood builds,my favorite one is this

 

[pdxmonkeyboy]

There will be so much bracing that the strength of the plywood will be a moot point. If your plans don't involve this much bracing then you need to go back to the drawing board. Google some builds over at monsterfishkeepers.com. Those guys build HUGE plywood tanks all the time.

 

[Shooter6]

^ definitely! I totally agree with you. There and youtube are two great resources for this!