Is this tank structurally sound?

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funkyaneurysm

Aquarium Advice Newbie
Joined
Feb 4, 2007
Messages
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I’m dying to set up this 290L (77 US gallons) tank as an Angel community. However, it clearly has a crack. The floor of the tank is comprised of three plates of glass. Can I safely use it?

The two base plates cover the entire floor but meet in the middle. So a top plate has been bonded to cover the thin gap where the base plates meet. It is this top plate that is cracked.

You can see from the photos that there appears to be, at the crack, dirt between the top and bottom plates – I suspect it was deposited by dirty water which leeched through the crack.

Importantly, there is no dirt between the base plates and the foam the tank is sitting on – so the tank seems not to have leaked.

However, I doubt the dirty water leaked between the plates while the tank was full – it probably leaked over the 10 years in which it sometimes was used to house and water pot plants.

So what do you think? Is it safe to use? If not, is it repairable?

Thanks!
 

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NO,,,it is not sound....the fact that the crack crosses the seam, and had already allowed dirty water between the layers, is a sure sign that it will eventually fail...I would replace the whole bottom, or scrap the tank
 
Welcome to AA! Personally I would not risk it, the weight of 77 gals of water is a disaster waiting to happen. I would contact a local glass company and inquire what a sheet of glass would cost to replace the cracked glass with no seams. It may be quite inexpensive to DIY repair yourself.
 
77 gallons. 8.2 lbs/gallon

631.4 pounds * 2.2 kg/lb

1389.08 Kg of weight on that crack. and a big one.


You wanna risk it?
 
Actually its 2.2 lbs per Kilogram so it is 287 kilos. I still would not risk it. That would be one heck of a mess.
 
I believe that you need tempered glass on the bottom to deal with pressure points caused by driftwood and rocks. Keep that in mind if you go to a glass shop. I think tempered glass is more expensive too.
 
It appears that the tank is frameless, and the bottom is upported by a stand that is covered with styro. If that is the case, than the bottom glass isn't carrying any of the weight, only transfering it to the stand. Large tanks (really long ones) are sometimes built with several pieces for the bottom. The joints are siliconed where they butt. No extra pieces are put over the joint, as the bottom is supported over it's entire length. A patch is necessary over a floating bottom. I, however, wouldn't trust patching a floating bottom; it would need to be replaced.
 
UPDATE

Last week I bought a pane of 6mm strengthened glass to replace the entire bottom. It cost me nearly $70, which is more than i expected, but bearing in mind I got the tank for free, I'm happy to pay that much.

I suspected it was going to be an absolute PAIN to replace the bottom. The bottom pane is not only siliconed to the side, front and back panes, it is also firmly bonded to the steel/aluminium L brackets which protect and hold each join in the tank. Unfortunately, in order to remove the bottom brackets which are bonded to the base pane, I'd also have to remove the vertical side brackets because they overlap. So this may turn into an entire dismantle of the tank.

PROBLEM 1
I was right. It's next to impossible to, using the only method I can imagine (using a blade), seperate the frame (pictured) from the glass. Mainly because there isn't a blade in the world thin enough to fit between the two.

QUESTION 1: Is it possible that the glass is joined to the frame using "super glass glue" and not simple, old, cuttable silicone?

QUESTION 2: How would you remove the frames?

NEW PLAN.
If I can't remove the two base plates, I shall simply remove the top plate and replace it with the new sheet I bought the other day.

PROBLEM 2
As the replacement glass is the size of the entire base, I have no way to get it in the tank unless I remove the support braces around the top (pictured) which I SHOULD be able to do - IF they are attached to the glass using plain old silicone - and NOT some "magic glass super glue".

QUESTION 3: How are these braces usually attached? Each brace has a small amount of silicone on the top edge, but it doesn't seem to be enough to reliably hold the braces up - yet I cannot see any other substance.

Any advice would be very greatly appreciated!

FYI - If I do succeed in removing the cracked top plate from the base of the tank it seems it could only be by spending a few hours using fishing line or picture frame wire as a saw. It's remarkably dificult to seperate two pieces of glasss with their faces siliconed together!
 

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Since I last posted, I have spent almost an hour trying, by using fishing line and picture hanging wire as a saw, to seperate the base plates. In that hour, I have managed to saw through about 1/2 an inch of silicone - which still leaves roughly 20 inches left. GGGGGRRRRRR. My triceps are not happy - the silicone really grips around the 'saw', creating an insane amount of friction.

So, I am considering 'Option 3' - keeping the cracked top baseplate in place and isolating it from water contact through the addition of 2 more plates of glass. See picture for 1000 words. The green plate is the cracked piece and the blue plates are the existing bottom.

The yellow top plate pictured may either be the full-length piece I have already bought (in conjunction with wider red pieces) or a smaller piece (as pictured). I would prefer to use new smaller pieces which I can get into the tank without removing the center braces etc from the top of the tank

QUESTION: Will this be sound enough?
 

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More power to you. at this point i would have broken down and baught a new tank.
 
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