How big with 1/4" Glass?

[Fluxion]

I have two pieces of glass laying around the shop that are 32"x74"x1/4"

I would like to build a tank but I am unsure of the maximum size for 1/4 glass. I tried the calculator on GARF and after playing around I came up with 18x18x48. I was wondering if it would be safe to change the dimensions to something like 18"x24"x48" if I was to weld up a steel frame to for the top of the tank which would be hidden by the canopy.

 

[Ghoti]

No don't do it

It's the height of the glass that is the critical factor. I believe a height of 18" or 19" is the maximum for 1/4" glass. GARF explains this somewhere. You can use all 72" in length but it will require cross braces. It is the weight of the water from top to bottom pushing out on the glass that will cause the glass to fail if you go too high.

 

[DeFeKt]

as soon as you get to 24" high you need 3/8 or more.

 

[Fluxion]

So do you guys think that 20" tall is feasable? I have another question, in the instructions from the GARF website it says to space the bottom up 1/4". Is this the best way to do this? I understand why you need to support the tank from the sides but will the silicone joint support 700-800 pounds of rock, sand and water?

Thanks for all the help. I love this place!

 

[bigsky]

my tank is 48x24x24 but is only filled to 22" deep and has been up for 3years 8 months with no problems. It is made of .25" glass and silicone only and the only bracing is around the top just inside and is 1.5" strip of .25 glass siliconed to front and rear panes and both ends with one across the middle making 2-2ft squares.

plate glass has a tensil strength of 10k psi so keep the tensil stress below 5k psi simply supported on all edges and you'll be floating your boat with a happy 100% safety margin.

build the tank with the bottom lying flat and the back glued onto the bottom then the two ends and then the front and then the bracing around the inside top. when I'm done with that I clean it all up and then run a fat bead of silicone alone each joint dressing them with a spoon creating a perfectly smooth curved wide seam. make sure glass is extremely clean with alchahol and dry.

when you put it on you stand, I put a 3/4" plywood panel ontop of the stand and then a layer of 1/2" closed cell foam them the tank. the foam (like a bed roll for camping) will not crush all the way and absourb any minute warpage and lumpiness and vibrations coming from the floor.

 

[DeFeKt]

in the instructions from the GARF website it says to space the bottom up 1/4".

personally i dont like that idea, like you said,
a 48x18x20 will hold around 250L of water, being 250kgs
800lbs of rock is around 360kgs
not to mention sand bead, driftwood and whatever other stuff you put into it..
ultimatly thats a 1/4" piece of glass supporting 3/4 a tonne of weight..
There is no way in heck i'd have that in my house, especially running off a 6 outlet power board which will be either directly underneath it or next to it..
Personally I don't like the garf standards they use, I don't think they thought about it very well.
Even the stand they descrive has the potential to warp twist, and crack or shatter the tank.
I'd recommend people stay away from GARF, but thats my personal opinion mate..
HTH

 

[JProx]

garf isn't that bad, i agree their aquarium building is a little lackluster, and i probably wouldn't trust it completely, their stand design is perfect though. i have built one about 2.5yrs ago, and have had it in use just as long and nothing has warped, twisted, etc and i have never heard anyone on the forum complaining about a garf stand failing.

warping is a defect caused by humidty and excess water being present as well as how the board was cut to begin with at the mill. if the right wood is picked out, and the stand is built and coated to resist water you will never have problems.

 

[greenmaji]

the idea behind the gap.. well commersial tanks have it with trim or just like garfs design.. and the reason is the glass has to have room to flex on the bottom..
when someone is having trouble with there all glass tank in posts on the internet.. well they didnt put the gap under the bottom glass... just a thought..

 

[bigsky]

You don't want the bottom of your tank to flex that is how they break.

build your tank with the bottom down flat and all the sides glued on top.
just besure to put a sheet of 3/4" plywood down and then a sheet of cork or styrofoam or closed cell foam down for your tank to sit on.

I use a 1/2" thick sheet of military bed roll it is dense closed cell foam.
the foam sheet is there to absorb and irregularities in your stand or spec of sand that might have gotten under the tank or any vibrations that come up from the floor.

I have build three tanks this way and have never had a problem even after moving from one house to another (I only have one in my possesion now and the other two are at my parents house).

I have a british book that talks about building a fish tank and it says that you should not build any thank with just glass and silicone bigger than 500 liters (about 125 gals.) and my calculator says not to go deeper than 22" with 1/4" plate to maintain a 100% safety margin (5,000 psi tinsel stress-plate glass rated at 10,000 psi tensel strength) I got this info and formulas from a mechanical engineer's handbook.

 

[bigsky]

oh yeah, that gap on the commercial tanks is there to replace the foam sheet.
the glass is raised so irregularities of your stand don't interfere with the bottom glass but it is supported by all edges with the frame were as Garf's are not. I would not trust garf's design either.

 

[greenmaji]

oh yeah, that gap on the commercial tanks is there to replace the foam sheet.

The foam sheet? does that mean everyone is suppose to put a piece of foam under there tanks? I know I never have(nor has most).. and the gap under all of my tanks has been all the way to all edges under the tank..

 

[Guest]

Most all glass aquariums have at least a 1/4" gap underneath for flex. The trim that is around all of them is practically that "trim". the silicone sealant used in aquarium making is quite strong when fully cured and can withstand considerable weight. This has been widely proven in the UK where most of their tanks have no trim at all... If you research this, I believe you will find this to be true also...

In the aquariums I have setup in the past, there has been no foam used and the bottoms were suspended.. no problems there...

Back to the question posed at the beginning, For safety, I would not go more than 48" long and 20" high for 1/4" glass. I looked at some new tanks to replace my 55 gal and all larger tanks than that were 3/8".

 

[bigsky]

here are two references for padding under your tank. they do not specify a manufactured tank of custom built tank.

 

[Guest]

Thank you for taking the time to show the articles... cool. I still don't do it, because the one thing pointed out, I use a commercially or professionally built stand. I agree with you that it is useful, I just stated I don't use it.

 

[Fluxion]

New Strategty

Since I started this thread I thought I would post an update as to what I have done.

I pulled the glass out of storage and found the stamp in the corner that says it has been tempered. Bummer

I called around to a few glass shops I deal with and priced glass for building several different sizes of aquariums. What I really wanted was a 90 gallon about 24" deep. Best price on glass $301 Had an offer for 1/4" salvage glass all I want for $60. Much better but I didn't buy it.

I must say that I really enjoy building things myself, sometimes more than the rest of the particular hobby. After browsing a fairly close by LFS with my Girlfriend on Saturday I found a deal. They had a 80 gallon Bowfront all glass aquarium and I fell in love. The bowfront is Awesome! I made a deal $200 for the aquarium, $70 for a Seaclone protein skimmer, a Magdrive 9.5 for $65. All I had to do is promise to buy more from them. No problem, out of the four LFS I have visited this was the only one worth dealing with. Besides the guy that helped us gave us ten gallons of water out of their ro/di system for our turtle tank including the two jugs!

SO Monday I moved the tank to a roller cart in my shop (I own a custom cabinet and millwork business) and the stand and canopy construction begins! I'll post pics when I'm done. It's going to be cool! I'm going to place the tank in my bedroom on a wall at the foot of my bed. All my furniture in the bedroom is black or bamboo. The stand and canopy will be Black with some bamboo panels and I might through some Jatoba in there somewhere since I have alot of it laying around right now ( I am building a curved staircase out of it right now).

My next step will be a few more questions coming in new threads. Thanks for all the help, this place rocks!

 

[fish_4_all]

Well this might help answer all the questions or just raise more.

I watched a tank built from sctratch that is 350 gallons. It is 24 inches high, 60 inches wide and 60 inches deep. The glass is 1/2" plate. The tank was made by raising the glass 3/4 inch of the bottom with a wooden frame around the entire tank. All the wood was sealed and primed before adding it to prevent warping. The bottom is supported by the thick excercise matting in one piece under the entire thing. It has been running for over 7 years and never failed or leaked.

I absolutely agree that the glass should have a pad under it and when I build my DIY tank it will have one. I also agree that the glass needs to be on the inside of walls unless you are protecting it better than the standard DIY tank. You commercial tank maker doesn't care about how long it last as long as it makes it out the store door and through any warrenty period. Take the extra steps to support your tank is it wider than the standard tank.

19" is the highest I would go for a DIY tank unless you are a real pro. This just gives you the leway for minor deviations in your assembly that oyu don't see in commercial tanks. If you are going more than 15 inches wide, put somehting under the tank that is not only strong but flexes enough to move with the tank bottom. There needs to be a much better book written on the needs for special tanks as far as glass and support. There isn't enough information out there to help anyone build a tank outside of the normal dimensions.

 

[bigsky]

one of these days soon I'll post the math and building of my tank and stand so others can figure out the stresses for them selves.
Give me a couple of weeks to get it done. I'll post it as a new topic, but will let you all know when it is up right here.