140g center brace down!

[jesusjones]

Any tank builders here? I've got a 6' long with ~20" water depth made from what looks like 3/8" (probably 9mm) thick glass. The center brace silicone failed and the tank bowed out enough for it to fall in. It was a DIY or local build of some sort. Back when I bought it I had been researching DIY tank builds and knew that the center brace (only 4") wide was too narrow for this size of tank. So, luckily, I only ever filled this tank to 3/4 full, knowing I should redo the bracing before filling it to the brim. Might of saved me from a big spill, but now I have a 1/2 full tank and really need to redo the bracing

How wide should the brace be?

I called a glass place local and it sounded like getting 9 or 10mm glass and then having it cut was gonna be kinda costly or not possible for him. Maybe I can source some glass and cut it myself, I've cut some bottles in half with a K-Tel bottle cutter so I am basically an expert ​

 

[AdoraBelle Dearheart]

140g... wow! Yeah, the tank failing would be a bit of a disaster...! Are there fish in there??

I think @Colin_T knows a good deal about this sort of thing, not sure who else might...

 

[jesusjones]

Yea it is my old goldfish tank, has a few fish left. I started researching again yesterday, my tank is 6' long and 24" tall (water depth) and with 9mm (3/8 glass) is near the limit for what the glass can handle (I think its technically OK, but no company would ever sell one). Adding a center brace will kind of divide the tank into two smaller tanks, so it is more like a two 3' long tanks which is more reasonable for only 3/8" glass. The center brace just needs to be wide enough so that the silicone has enough surface area to hold onto so it doesn't rip apart again.

The original brace would of had only given 1.5 square inches for the silicone to bond to and with 200psi strength silicone it would support only 300lbs of force before it failed. A 12" brace will be able to support closer to 900lbs before it fails and the tank holds 1200lb of water. So I feel like the 12" brace should have enough "stick" to hold it together. ​

 

[Glenn407]

Does it have to be glass? I'm guessing this is a brace in the center going from front to back? A pic of the tank and whatever you have typically on top would be helpful. I can think of a number of ways to go but can't be sure without a visual.

 

[Colin_T]

Tanks that are 6 foot long usually have 2 cross members but not always. The cross members are normally around 4 inches wide and made from the same thickness glass as the aquarium (9-10mm, with 10mm being common, 9mm is unheard of).

If you use a glass silicon for aquariums (it will say suitable for aquariums on the tube of silicon), it should hold up without any issues.

Make sure the glass is free of oil, grease and dirt. Usually you wipe it down with alcohol and dry it off with a paper towel or tissues.

Let the silicon dry for 7 days before refilling the aquarium.

 

[jesusjones]

Does it have to be glass? I'm guessing this is a brace in the center going from front to back? A pic of the tank and whatever you have typically on top would be helpful. I can think of a number of ways to go but can't be sure without a visual.

It is front to back, I remember reading that using the same thickness of glass would help to reduce stresses that could occur if you made too stiff a brace. Or breakages from one that's too weak.

Tanks that are 6 foot long usually have 2 cross members but not always. The cross members are normally around 4 inches wide and made from the same thickness glass as the aquarium (9-10mm, with 10mm being common, 9mm is unheard of).

If you use a glass silicon for aquariums (it will say suitable for aquariums on the tube of silicon), it should hold up without any issues.

Make sure the glass is free of oil, grease and dirt. Usually you wipe it down with alcohol and dry it off with a paper towel or tissues.

Let the silicon dry for 7 days before refilling the aquarium.

Just eyeballing with a tape measure the glass looks just under 3/8", I will get a set of calipers on it though. I think I will try and make 2 braces as you say. I already have one, so I just need to make up one more and it should work better lighting wise. In the days before photobucket went down I remember seeing stress and deformation plots on tanks with central, dual and euro bracing and IIRC having multiple braces (front to back) was usually superior to a single larger one. So it sounds like a good plan too.

Will work on getting the supplies and report back

 

[Glenn407]

I don't know why you couldn't just use even a piece of 1/4" plexiglass.

 

[jesusjones]

I don't know why you couldn't just use even a piece of 1/4" plexiglass.

The plexiglass would probably be OK if you could bond it reliably to the glass. I'm not familiar with bonding to plexiglass, but I know glass on glass with acid cure silicone works and is forgiving to rework if needed.

 

[itiwhetu]

If this tank is made of 9mm glass at that depth the minimum glass thickness is 12mm. If I were you, I would start again and not refill this tank, above around 8-10 inches.

 

[jesusjones]

If this tank is made of 9mm glass at that depth the minimum glass thickness is 12mm. If I were you, I would start again and not refill this tank, above around 8-10 inches.

Even without bracing filling to 18" on this tank (even with 9mm glass) should have an OK (above 3) safety factor (based on some charts and calculations) for bowing/bending failure. Maybe its not enough surface area for the lower silicone seal to handle the pressure but the glass should be OK.

But I will keep it around 10" in its broken state until I have 2 braces on it, then I will keep it around 20" for some peace of mind.

 

[jesusjones]

I'm not a tank building expert though, so don't do what I do or take my advice, but feel free to watch

 

[itiwhetu]

As long as you feel happy with it, and it doesn't stop you sleeping at night.

 

[Colin_T]

what are the tank dimensions (length x width x height)?
Length is 6ft
width is
height is

Aquariums that are 2ft high are usually made from 10mm thick glass if they have support straps.

Aquariums that are 18 inches high are usually made from 6mm thick glass, if they have support straps.

 

[itiwhetu]

what are the tank dimensions (length x width x height)?
Length is 6ft
width is
height is

Aquariums that are 2ft high are usually made from 10mm thick glass if they have support straps.

Aquariums that are 18 inches high are usually made from 6mm thick glass, if they have support straps.

The minimum for a 6 foot tank is 10mm glass sides and a 12mm base, in my book. Anything less than that and I believe you risk failure.

 

[Colin_T]

The minimum for a 6 foot tank is 10mm glass sides and a 12mm base, in my book. Anything less than that and I believe you risk failure.

It comes down to height and width too. We have 6ft x 18in x 18in tanks made from 6mm thick glass with 2 cross members and they are fine.

If the tank is 6ft long x 2ft wide x 18inches high, we would have a 10mm base and 6 or 8mm sides with 2 cross members.

If the tank is 6ft long x 2ft high x 18-24inches wide, it is 10mm all round with 2 cross members.

If you don't have support straps and cross members on top, then increase the glass thickness by 2-3mm.