How is it not evenly distributed if everything is level? How could I tell otherwise that something isn't right?
Leveling of my 600 Gallon.
- Thread starter neoprodigy
- Start date
You using the shims makes it so the weight isn't evenly distributed over the bottom of the tank, duh. A tank not being usually level caused the weight to be unevenly distributed, which causes seam failure, but uneven weight distribution can also happen if the tank isn't leveled properly, like in your case.
But shimming under the plywood makes it level? Or is the level itself lying to me now?
You are missing the point. Yeah the tank itself might be level if you shim between the tank and the plywood, but shimming between the tank and the stand creates a stress point, and that stress point will cause the tank to eventually fail. You have two options here. Either level the tank properly, or leave it as it is and wait for it to fail. If you don't level it properly, it will eventually fail, and when it does, you will have no one to blame but yourself.
Well I've been trying to shim under the stand legs as well, but it's not changing anything.
You need to drain the tank and level it. Maybe the plywood has become warped since the stand isn't level.
Eventual fail may be a bit of a stretch. The main issue comes when the tank is not level in two directions x-y. This causes the acrylic/glass to twist creating failure. If the tank is only off in one direction, say from left to right it may last a lifetime.
When a tank is perfectly level the only pressure exerted on the panel is in the x-y direction. By making the tank off level the panel is no longer at 90 degrees so expieriences very minor Z component forces. Now since the force on the panel is always equal you can create a simple mathmatical equation to solve for the Z component. To do so sigmaSx+SigmaSy= SigmaSz+SigmaSx+SigmaSy. Where sigma Z, X, Y can be solved using vector components of the cos/sin of the angle. This type of calculation I have not done in a while I may add. However the ratio between total stress and additional stress stays constant if the forces are at constant angle with changing water volume. Say there is a 1/4” difference from left to right and nothing front to back so the tank still sits perfectly flat on a surface. The additional water exerted on the side panel in the Z direction will account for under 1% of the total stress on the panel (if I remember the calculation it was closer to .5%). Given any standardized level of safety .5% is greatly inside the safe range. The key to this calculation is that the tank is still on a flat flush surface.
Now to solve the issue of the tank in this thread. If he shimmed between the plywood and the stand properly the weight of the tank will be evenly distributed. To do so, every spot of the tank that is not touching the plywood will need shims, you would need to go under and around the outside of the tank. I agree with both members in what they said above. I would start by checking what
CarpCharacin
suggested and take the tank off the stand and ensure both the metal and plywood are level. Personally I think the acrylic tank itself may have a very slight bow on the bottom as a result of cell structure collapse of the foam. My reasoning for this is based on where the tank is raised. To me it looks like it’s the front right corner. Assuming the tank is back heavy and there is a slight bow in the bottom the front should be slightly raised. If after the tank is off and the stand is level I would place the tank back. If it’s still raised in the corner then you know the acrylic is bowed slightly. This is when the discussion gets interesting. Should the tank be filled as is and have the acrylic contort to the stand or should the tank be shimmed. If the stand is perfectly level but the tank still does not sit flat I would shim between the plywood and the tank creating a flush even contact between tank and stand.
I understand what carp was trying to say about the shims but unfortunately/fortunately the physics won’t create a point pressure as long as the entire base is still in contact with the plywood and the plywood and shims still make contact all throughout the stand.
My opinion is shim the plywood. I will happily hear out others in why they would do differently.
so I replace the board with 3/4. now I think the issues is the tank.
the board are touching the stand.
There are the 2 corner that is not touching the board
the board are touching the stand.
There are the 2 corner that is not touching the board
Can you place a 6' level going from corner to corner cross-wise, such as in your picture? What does the level show?
