Acrylic tank blow up...

[drewread]

Well.. I just tried to build my refugium out of 1/4" acrylic and failed miserabley... the dimensions are:

12.5(W)x19(L)x24(H) and it was all 1/4" acrylic.

I used WeldOn #4 to glue it together...

Luckily I tested it outside with tap water before I filled it in my basement...

Two of the sides were 12.5 x 24" the other sides were 18.5 x 24"

The bottom was 12x18" and was set up 1/2" from the bottom of the tank.

This gives me a volume of approx 22 gallons...

What I am wondering is how I can make this thing stick together!?!

There was some major flexing of the long panes of plexi which I imagine contributed to the failure. What types of bracing can I use to stop this from happening or are there any other suggestions that anyone has?

Thanks in Advance

 

[Anonymous]

1, make sure you are cementing it correctly, e.g., no bubble, and all joint is clear and "professional".

2, make sure you use casted acrylic and not the extruded (cheaper, softer) or coated (anti-scratch, which is good as a windown, but hard to work with)

3, make sure the design is done appropriately, e.g., with appropriate bracing or reinforcement as needed. Look at some of the commerical sump of the same size, and see if you can learn from the design.

 

[Arch01]

Try this. There is a link for an Excel calculator at the bottom. 24" is way too tall for 1/4" material, even with bracing.
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[rabagley]

You don't mention the top piece of acrylic. That sixth panel to complete the box, with holes cut out for access to the interior, will make all the difference in the world to the strength of the completed box. My own estimate is a 200-300% improvement in the corner seam strength when adding a top panel. I recommend leaving 1" around the whole edge and find some way to leave a little extra material in the corners. A 2" radius to the corners would be perfect. Don't cut any sharp inside corners in acrylic that's going to be stressed. A 1/2" flush-cut router bit with a slapped-together MDF template underneath will do fine.

As for the thickness, I wouldn't be too worried about 1/4" cast acrylic sheet. Cyro's thickness calculator would have you buy 1" thickness acrylic for a 10 short if they thought they could get away with it. Their recommendation of 3/8" on your box with a closed top sounds really conservative.

My old 33 breeder was 18x17x30 (HxWxD), and made from 1/4" cast acrylic, which included a 50% safety margin. Cyro says that 0.4" is the minimum I should have used (even thicker than for your tank). There was a bowing in the middle of the front panel of the tank, but you needed a pretty good straightedge to measure it.

I would sand the first glue joints down to smooth plastic before regluing. It will look a lot better and be substantially stronger if you take the time to make a nice surface inside the joints.

Regards,
Ross

 

[jcato]

having the bottom raised up 1/2" caused more pressure on the sides and that is why it probably failed, the bottom should rest flat on a level surface.

john

 

[Anonymous]

I take that to mean that the height of the sump was 1/2 inch higher than the tank, not that one side is taller than the other, or the bottom is not "water flat."