Acrylic Tank has arch in center?

[Sea Bass]

Has anyone ever had a large acrylic tank that has a slight bow in the upperward directoin in the center of the tank?

I have a 300 gal acylic I bought that when put on the stand seems to have 1/8" gap at the very middle from front to back. I have this tank sitting on 3/4 in. plywood with another 5/8 in. foam board on top of that for leveling purposes.


The tank was previously filled and ran for many years in a pet store so its not a new tank. Is this normal or should I be concerned? Im at the point Im ready to start adding the reef rock and dont want to take any chances on going further if THeres a defect I should be concerned about.

Anyone with some insight or expierence and advice would be very much appreciated.

 

[DAHansen]

Just out of curiosity, have you taken a level to both the tank and the stand to make sure it is the tank, and not the stand?

I don't have any experience with acrylic tanks, but I can't think of why it "should" be bowed, when they are supposed to be fully supported across the bottom.

 

[PEMfish]

If the sides are sagging down then there is most likely a huge stress on the front and back panes. The only way to know if this is a problem is find out;
is it like this empty on a flat surface ( not the stand or floor ) and is the stand bowed.

 

[Frankie]

1/8" is nothing to worry about with a 300. Whats happening is the foam your using is too soft and the outer edges are pushing into it. If you want to correct it use a thinner more dense material.
Welcome to RS Cannot wait to see the pictures of this beast!

 

[Sea Bass]

1/8" is nothing to worry about with a 300. Whats happening is the foam your using is too soft and the outer edges are pushing into it. If you want to correct it use a thinner more dense material.
Welcome to RS Cannot wait to see the pictures of this beast!

Thanks for the advice Ill try a denser foam and see what happens. Im using a typical piece of blue colored foam from a Home improvement store.

I can see if there is something else available

 

[PEMfish]

I wouldn't bother taking it down for a 1/8" bow in a 300g.

 

[Varga]

How thick is the acrylic? I wouldn't worry about it for another 4-5 years. unless you have the 1/2" acrylic in which case I would do some research.

 

[lcstorc]

Better safe than sorry. If Frankie advises changing it out then I would do it.

 

[BigAl07]

There IS a thinner foam... actually a couple of options...


#1 is 1/4 foam usually used for "Mobile Home" skirt insulation. Drawback here is it's only sold in like a 50' Fan-Fold bundle. If you know someone who has a small piece it would work good.

#2 is the foam used under "Floating Floors" (Frank knows what this is called better than I do) and I know of several people who have this under their tanks long term.

The benefit of thinner foam is it doesn't have so much "Give" which could actually put pressure in an area that isn't designed for pressure.

Good luck and Happy Reefing