View Full Version : Is this tank structurally sound?

02-04-2007, 03:48 PM
Is this tank structurally sound?

Im 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?


02-04-2007, 03:55 PM
I tend to err on the side of 'chicken'...unless you were willing to first give it a 'test-run' it over a concrete floor...near a drain...I'd avoid it...

02-04-2007, 04:09 PM
Ditto!! I'd also err on the side of caution on this one.

02-04-2007, 04:44 PM
i wouldn't use it unless you replace the bottom plates. welcome to a.c. too!

Lady Hobbs
02-04-2007, 05:15 PM
Scary. I assume the bottom plate was added when the crack was discovered or did it come with two plates, do you think?

I would seal off the cracked plate with aquarium glue very well and when cured for a week, fill the tank with water and let it sit outside for a week just be play it safe. However, I don't know if you will ever be able to rest completely knowing it has had this repair and worry about it constantly.

Perhaps you could use it as a terrarium for plants, snails, frogs, etc?

02-04-2007, 09:15 PM
If the crack was on the back or the side I would do as hobbs has suggested. On the bottom... I don't have the courage for that. 77 gallons is a lot of water and a ton of weight on those bottom plates. Add rocks and decor and it's too risky for my taste. I would be very afraid I would wake up one day with all dead fish and 77 gallons worth of water damage.

02-04-2007, 11:29 PM
I would replace the top plate and reseal the entire tank just to be on the safe side.

02-12-2007, 02:09 PM
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.

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?

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.

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!

Lady Hobbs
02-12-2007, 03:20 PM
Is it possible to just silicone all sides of the replacement glass and add it in thru the top and silicone sides again? I don't know if this can be done but it sure sounds easier than tearing apart all the existing seams.

02-12-2007, 03:53 PM
Hobbs, I think what you mean is the problem I described in "problem 2" (above). The replacement glass can't be lowered into the tank because it won't fit past the braces (pictured above) that line the top edge of the tank - so I'd have to remove those - but I am unsure how if they are attached using more then the meagre amount of silicone visible.

I would also have to remove the cracked top plate on the base because it only spans 1/3 of the tank and hence forms an uneven bed for my new replacement piece which extends to the extremities of the tank. Under the weight of the water, the replacement galss wouldn't last long on such an uneven surface.

My only other option would be to buy 2 narrow lengths of glass the same thickness as the cracked top plate and place them either side of the cracked top plate to guard against leasts from the side. I would then buy another piece of glass which covered all 3 to guard against leaks from the top.

02-21-2007, 04:10 AM
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 1/4 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 pictures above 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?

02-21-2007, 04:13 AM
I'm trying to find a link, but I'm fairly certain they make wire saw's, ie wires with serrated edges. I'm not sure if they will fit into the crack though.

03-01-2007, 04:33 PM
Instructions to solve your problem:

1. Return the glass plate if possible for a refund.

2. Take the refund and go to the nearest bargain pet supply store when they have a sale.

3. Purchase a new 75 gallon tank for approx $200 on sale.

4. Throw the old cracked tank off the nearest cliff.

5. Close your eyes. Sigh and smile in pleasure at the sound of splintering glass on the gentle breeze.

6. Laugh maniacally until the urge passes!

Sorry, not very helpful I know, but it sounds like you're investing in a lost cause. You could easily earn enough to buy a new tank with the time you're investing in the old one. From the sound of it, this tank may have been previously repaired and likely "Gorilla glued" back together. The only reason I can think of for the two plate bottom is that someone ran into the same problem as you are right now. They used overlapping glass plates as the solution and as a result, the tank is once again broken. Let it go to it's grave peacefully, without further mutilation.

Lady Hobbs
03-01-2007, 04:45 PM
I priced a 75 gallon just yesterday. $129.95. Of course PetSmart had to be $40 more than this small pet store! grrr And wouldn't you just know it, I have a $75 gift certificate at PetSmart but won't use it for jacked up prices!

butters, I'm so sorry this tank has been such a pile of work and money for you. Did you fill it up some to even see if it leaked? I wouldn't toss it over a cliff but maybe you can use it for plants (in pots) a reptile or something and just chalk this up to experience.

03-01-2007, 11:00 PM
OK, maybe tossing it off a cliff was a bit dramatic, but I don't think it's worth trying to fix as an aquarium. It would make a fine terrarium though! Perhaps you can use it for an amphibian, snake, or Green Anole habitat. At least you could probably sell it as such.

Lady Hobbs
03-02-2007, 12:19 AM
He probably feels like throwing it off a cliff at this point but a terrarium would be great. Or sell it for the $70 he paid for the glass.