glass thickness question

[stinger]

Hi,

I've got a question regarding glass thickness for a tank. Right now i'm having a tank made, it's going to be 12mm thick glass, tank size is 8 feet long, 3 feet wide and 2.5 feet high. Is this enough thickness?
I just want to double check whether this is OK.
Last time the tank was built using a 10mm glass, after it was filled with water, 10 minutes later the bottom of the tank broke and the saltwater ruin my house floor.

Thanks

 

[Anonymous]

Its always good to use something like GOOGLE for questions like these

I have no idea if that is thick enough personally, but this site: http://saltaquarium.about.com/cs/aquari ... omtank.htm

Lists that size tank with 20mm glass

The only two measurements that matter by the way are the length and height of the largest side.

If you go to this page: http://www.google.com/ and type Aquarium thickness calculator you will get a whole bunch more links to go check on...


HTH

Bryan

 

[Steven]

FWIW, my tank is 7' long X 2" wide X 2.5' high. Glass is 3/4 inch (18.75 mm) thick. The manufacturer didn't think 1/2 inch (12.5 mm) thick glass would be strong enough in the long run. Maybe he over did things but I set up the tank last March and it's still intact. Better safe than sorry when your talking about so much salt water.

 

[Steven]

Sorry. The above post should say 2' wide, not 2"!

 

[Ninong]

Right now i'm having a tank made, it's going to be 12mm thick glass, tank size is 8 feet long, 3 feet wide and 2.5 feet high. Is this enough thickness?

NO!

I don't know of any U.S. or Canadian manufacturer who would be willing to build that tank with 12 mm glass.

As a point of reference, I have discussed this question with a custom tank builder in Canada and he told me that the largest he is willing to go with 12 mm glass would be 96" x 24" x 24" or 84" x 32" x 26" or 72" x 27" x 27". Those three different sized tanks he has already built using 12 mm glass (with euro bracing and cross bracing) but for any tanks larger than that, he insists on using thicker glass.

Here is a New Zealand website with an excellent glass thickness calculator: http://www.fnzas.org.nz/articles/techni ... thickness/

 

[Len]

12mm is frighteningly thin for a tank that size. For your reference, my tank is 52x28x28 and I use 12mm (1/2") glass.

 

[Unarce]

I even have 12mm on my 90g.

 

[melas]

they are using 600mm (26inches) glass at the okinawa aquarium. . . just for reference. . . haha. . . i can't imagine an additional 2mm making you feel any safer after one broke on you already. whatever the extra cost (for 20mm) it would certainly be worth it!

here's a cool link to a pic of the okinawa aquarium. . .
http://www.trekearth.com/gallery/Asia/Japan/photo59931.htm

 

[Ninong]

they are using 600mm (26inches) glass at the okinawa aquarium. . . just for reference. . .

Actually it's not glass, it's acrylic. It's 10m deep, 35m wide, and 27m long. The thickness of the acrylic viewing panel is 600mm (23.622"). It holds 7,500 m3 of water. That's according to their original website when it was first opened three years ago.

 

[stinger]

thanks for the info and the link.
i've used the formula provided by the NZ site and it even has the excel spreadsheet to calculate the tank size as well.
I've decided to reduce the aquarium to 8 feet long, 3 feet wide and 23 inches high (i can't change the length and the width because the stand is already been made). This specification leaves me with 12mm glass thickness.
Now my question is how reliable is their formula? and has anyone use this before?

 

[stinger]

forgot one thing, what does it mean by safety factor? how can someone quantify that?

 

[stinger]

Here's the pic of the broken tank.
The stand will be modified as well, because i think that was the culprit (the gap between the beam is too big)

 

[dizzy]

Here's the pic of the broken tank.
The stand will be modified as well, because i think that was the culprit (the gap between the beam is too big)

I don't believe the spacing between your bottom braces was the problem. From your pictures it looks like the glass cracked from the bulkheads out. The bulkheads may have been over-tightened. It doesn't take tremendous force to keep them from not leaking. Something like hand tight plus a quarter turn with a wrench is usually sufficient.The bottom glass definitely looks thin to have holes drilled in it. If the stand is not completely level it can put extra pressure on the high spots. Try to check to make sure there are no high spots.
Mitch

 

[stinger]

well i didn't built this tank myself, i had someone else did it for me so i wouldn't know if it's overtightened. but i will make this point to the tank maker. The bottom glass is only 10mm, what size of glass would be all right then?

 

[Ninong]

My little 120-gal tank has a 19 mm bottom and 12 mm sides. If I were having a tank built to the dimensions that you're talking about, I would make both the bottom and the sides 19 mm.

I'm not comfortable with telling you what you should do, therefore I simply told you what I would do. This is based on several conversations over the past five years with someone who builds tanks for a living. However, I am comfortable saying that 12 mm is not sufficient for a tank the size you are planning.

 

[Anonymous]

The link I gave you in my post has a table to use. No calculation required...

If the tank is 3 foot wide and 8 foot long then that is the biggest piece of glass, that is the one you need to go by.

Using that link I gave you says 20mm glass.

Might be good to get an opinion from another tank manufacturer

 

[stinger]

Please correct me if i'm wrong,going by the website for 8 foot long and 2 foot tall aquarium, glass size is 12mm. The excel spreadsheet that i got from the NZ website also comes up with 12mm thickness.
There are 2 methods to determine the thickness of the bottom glass:
The first one is if the tank is only supported by 4 edges of the stand,
the second one is if the tank is uniformly supported then the same glass thickness can be used (eg. 12mm)

Also if you drilled a few holes (4) to the bottom glass, does it make it weaker? is it safer to drill the top side of the tank for the overflow and run a pipe through the outside to the sump underneath, instead of running a pvc pipe through the bottom of tank?

Thanks

 

[Anonymous]

i have a question about you're pictures. the first one shows what looks like to me two holes in the bottom on opposite sides of the tank.unless i am not seeing this correctly, how did the tank rupture in two different places at the same time ?

 

[Anonymous]

Hot damn I think I found your problem...


The last post made me look back up at your pictures. If the bottom glass is sitting on top of that styrofoam, then you have one of those tanks where the bottom is fully supported by the stand.

You have to have plywood under that styrofoam, the styrofoam won't support anything evenly, its just there to absorb small imperfections in the plywood.

You might want to check into that, I am almost absolutely positive about that....

 

[stinger]

Yes there are two holes in the bottom on opposite sides, and unfortunately i wasn't there when this all happened nor anyone saw it happened. It lasted only 10 minutes after it was filled with NSW and the guy left, still working in the office when wife rang histerically, didn't even get a change to look at it with all the LR and NSW set up
My guess is it started to shattered in one place and because of a big vibration form the first one, the other side gave in as well

The tank maker also wanted to modified the stand this time using the plywood under the styrofoam, i'm glad you suggested the same thing as well.

I also checked out other fish shop, they've got a display thank with dimmension 8 foot long, 2.5 foot wide, and 2.5 foot tall made with 12mm glass (all sides and bottom), tank is supported by the stand and when i looked underneath it's got a piece of plywood (don't know the thickness of it). It's got a list of different size tanks and i notice only when it's taller than 2.5 foot (3 foot) that they're using 19mm bottom but still 12mm for the sides.

Another shop, the display tank is 10 foot long, 2 foot wide and 2.5 foot tall, i saw it was 12mm glass for all sides, i dont know about the bottom glass but.

So i dont get it, but down here it seems everyone is only using 12mm glass most of the time. I guess maybe because it's pretty stable here, we have got no earthquake even minor one