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Re: Large tank construction

> Michael, or any one else that has built plywood tanks, I have a
> question for you. For an 8 foot long tank I am thinking of using 1/2
> plywood for the faces. (Probably will use birch veneered cabinet grade
> so I can get a nice stained finish on the outsides). I am not sure if
> I want to use thicker than 1/2 inch for the floor or not. What do you
> think?

I would most definitely use 3/4" all around.

> I am thinking about cutting a groove (dado cut) in the face pieces
> about 3/4" above the bottom then inserting the floor in this groove .
> Then adding strips under the floor running across the width ever 2
> foot. Then the floor would have some reinforcement.  I could also
> build the cabinet with a solid top so that the load would be spread
> over the edge of the tank and the strips running across the tank too.
> Floor size should not be a big problem then. (Humm, guess I answered
> my own question there! )

The reason for raising the bottom in glass tanks is so that 
irregularities in the surface the tank sits on will not crack the 
glass.  This is not a problem with plywood.  I would let the bottom 
be the bottom and not worry about the strips.  Just make sure the 
cabinet supports the bottom well.

> I have also settled on coating the inside with epoxy resin (not paint)
> and then adding a layer of light weight glass cloth like I used on my
> kayak with another coat of epoxy resin. This will tie all the pieces
> together as one big unit and make it much stronger. And of course make
> it hold water a little bit better! <G>
> I obviously I will have to have braces across the top of the tank. I
> am thinking of using a 2"-3" wide piece of plywood, notching the top
> of the tank and epoxying it in place. I would like to just use one in
> the center but I suspect that will not be adequate. Anyone know for
> sure? I know that to much is always better than not enough! I will
> most likely use 3 braces just to be sure.

You will want to reinforce the top edge all the way around.  Like a 
2X4 on the inside top edge?  Two cross braces would be good, but 
they tend to get in the way of things.  I don't think the epoxy is 
stong enough to hold the cross braces.  My idea is this:  Get a piece 
of rebar and cut it a little bit shorter than the outside width (so 
you can hide the ends) of the tank.  Thread both ends.  Use a 2x4  to 
hide the rebar by cutting it in half lengthwise and cutting a dadoe 
out of the center, and then gluing it back together.  The rebar will 
run inside the hollowed out 2x4.  Drill a hole through the sides of 
the tank where the rebar will come through, and drill a countersink 
on the outside so the rebar and the nuts (you thread 'em onto the 
rebar so the tank walls don't spread) don't stick out.  You can cover 
'em with a plug when it's assembled.

Do this twice for 2 top braces.

> Where can I find information on sizing glass? I know that I have I
> have seen this on the web but I didn't save the site. Anyone know?

You can use 3/4" acrylic.  It's lighter and cheaper.



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