My new 2600 gallon plywood tank project

  • We are currently upgrading MFK. thanks! -neo
Plywood will be going over the inside frame as well. Will be using screws and glue on the plywood as well. This way the Pond Armor won't have issues with the metal.

And the air gaps are in the plywood from the manufacturing process. If you look at the edge sometimes you will see little rectangle gaps.
 
So looking at your pics I also have concerns about the butt joints with the hangers and the hangers being on the inside of the tank. If you are going to glue and screw plywood to the inside I don't think it will sit flush with the hangers and screw heads on the inside. I would remove the inside hangers and screw the plywood with glue making sure to overlap the joints. I would also add a top plate to the 4x4's to add strength to the butt plate. Looking at your front panel a 2x6 or 2x8 laid down with the joints overlapping would really sure up the front panel. Kind of like euro-bracing. These where just my two thoughts when I saw your pics and then I read on to see you have concerns as well.
For the ply would mix some epoxy with around 10% acetone to thin our and apply it with the sheets flat and screw them in after they dry. If the ply is dry it should absorb the resin and help fill in the air pockets. Yes some people have built tanks with 1/2" ply but it also matters the grade. I can't remember his name right now but I am sure you read his builds, but the guy in Hawaii used all furniture grade hard wood with is much stronger than a standard ply.
 
Ok.. Last night we made some modifications to the middle uprights.

Pictures later tonight.

Basically we ran an 8" long 1/2" lag bolt down to the bottom of the base through the bottom outside section of each upright. This will tie in the bottom more and provide a much more stable mounting point so there is no threat of an issue down the road. Then I moved the T brace from the inside to the outside of the tank.

Admittedly, This is a design flaw that I didn't consider because my last tank didn’t need center supports. And the only other source I knew about on here for this info did all his updates in YouTube videos and removed them all so I couldn’t reference them.. (Ahem.. not going to mention names.. J )

What I should have done was run these 4x4s to the floor and tie them in that way. Live and learn I guess. It’s not a show stopper and I am glad I had a couple of guys who know about this stuff look at the setup last night and give me some input. At least I was able to make these modifications and make it safer.

On the top beams I left the outside brace in place, removed the inside T brace, and added a 3’ piece of ¾” plywood to the top and mounted the cross brace brackets with 6” lag bolts through the top of the beam.

Tonight we will finish up with the plywood on the inside of the tank and start to lay the bondo down and get back on track.

 
I have been reading this build, and I read your last one too. They have both been helpful to me in figuring out some of my issues I was having with my design.

I am not quite tracking with the first lag bolts your talking about are going, and in and which boards they are going. I have read it 4 times and its just not sinking in. I got the second set figured out, just not the first. I may just be tired but in my mind those bolts are just acting like big screws, which can't be right. Clarification please?
 
As they say "a picture is worth a thousand words" that picture explanes it well. I was really confused by what you were saying but now I get it. I was thinking something similar but going straight down through the post. Glad to know I wasn't totally out there in left field.
 
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