Bracing a plywood tank

[Night Ranger]

I'm going to be adding a 2"x2"x8' long steel square tube across the back of my plywood tank. The dimensions of the tank are 8' long 37.5" tall and 4' front to back with 2" thick walls and bottom. Water level will be at 32.5". There will be 3 braces across the top when it is finished. My question is would it be best to put the brace across the center from the top and bottom of the water level or put it at the center of the overall height of the tank. Note the overhead crane for lifting the panels into place.

 

[tomojsg]

 

[LBDave]

Nice. IDK. Sounds like I would want the steel braces as high above the water as possible (if that's what you are saying). So what goes in the front? Plywood with a window?
Just looking at this I'm wondering why not a plywood top? Similar to an acrylic tank. Theory is the bottom and top hold things together. Mid height when then be my concern.
Looks like a lot of work. Did you consider acrylic rather than plywood before you started the project? (just curious).

 

[Night Ranger]

There will be 2x4 bracing hidden inside and across the top and around the inside perimeter. I have a piece of 3/4" low iron glass mounted inside a 2" thick plywood, fiberglass and epoxy frame ready to be installed with the overhead crane. I was thinking about a acrylic tank but they scratch so easy. I've seen closeup pictures of acrylic aquariums after some years of use and I was shocked at how many hazy micro scratches were in the acrylic. Kinda offsets the saying that acrylic aquariums are crystal clear.

I've decided to go ahead and attach the viewing panel and seal it into place, after I install the cross bracing I will add water and monitor the panels for deflection at that point I will decide how I will approach wall bracing. I'm pretty sure there will be some steel bracing needed. I would have used 2x4s for exterior bracing but this is going to be in my livingroom and I don't believe exposed 2x4s would be appealing. Pictured below is where 98 screws will be used with epoxy adhesive to attach the bottom of the front viewing panel. The back and sides were attached in the same manner. Remember all plywood is laminated and is 2" thick.

Thanks for the reply and interest as there will be a lot of pictures in the future.

 

[LBDave]

acrylic DOES get scratched up. And it frustrates me because my acrylic tank gets sun. So algae grows and I have to scrape it and brush it. But it's in my living room so I rest in that it should not leak.
My dad and I built an 90 gal plywood tank when I was a kid. Brings back memories. We put it together. Torched the outside for that special look. Fiberglassed the inside with embedded gravel and rock on the sides. We coated the exterior with the fiberglass resin. My dad brought home some high-rise grade glass and we silicone it to the front opening.

 

[LBDave]

Testing/observing the tank for deflection after it is filled is a great idea

 

[homer1983]

mine is pretty close to same dimensions, 91x42x34. I used 3/4" plywood for the main"box" then trimmed it out with 3/4". The top 2 braces are also doubled up 3/4" plywood. The deflection is miniscule, I can't see it with naked eye so if it does bow out, it isn't noticeable. I didn't use any dimensional lumber in the tank itself, all plywood, screwed and glued using t88 epoxy. The top part is a basking area.

 

[LBDave]

Is this tank filled with water yet? Any pics?

 

[Night Ranger]

Is this tank filled with water yet? Any pics?

I'm slowly working on it. I've been up and down with a lot of back procedures lately and the doctor has me sedated to the point I won't drive. Currently working on the plumbing for the reverse flow under gravel filtration. Lids with stainless steel hinges and latches are completed, needs to be reinstalled. Inside supports for the lids are completed but needs to be reinstalled. Under gravel filter grid with screen is completed, needs to be installed.
I will work on the aquarium for an hour or two then take a few days off. Once it's done it should be a super nice aquarium. The tank is two inches thick, made from plywood with a full fiberglass and epoxy interior with a 4'x8' base. The height is 37.5". The water level from the top of the gravel to the top of the viewing opening minus 4 inches front to back and side to side because of the thickness of the plywood will put it right at 508 gallons. If I calculated the overall outside dimensions like aquarium builders do, then the aquarium would be at 748 gallons. Big difference! There will be a lot of pictures. Sorry for the late reply.

 

[LBDave]

Ok.

I'm slowly working on it. I've been up and down with a lot of back procedures lately and the doctor has me sedated to the point I won't drive. Currently working on the plumbing for the reverse flow under gravel filtration. Lids with stainless steel hinges and latches are completed, needs to be reinstalled. Inside supports for the lids are completed but needs to be reinstalled. Under gravel filter grid with screen is completed, needs to be installed.
I will work on the aquarium for an hour or two then take a few days off. Once it's done it should be a super nice aquarium. The tank is two inches thick, made from plywood with a full fiberglass and epoxy interior with a 4'x8' base. The height is 37.5". The water level from the top of the gravel to the top of the viewing opening minus 4 inches front to back and side to side because of the thickness of the plywood will put it right at 508 gallons. If I calculated the overall outside dimensions like aquarium builders do, then the aquarium would be at 748 gallons. Big difference! There will be a lot of pictures. Sorry for the late reply.

Ok. Be careful of your back. Look forward to final pictures.