300 Gal beauty cracked bottom. Any hope to repair?

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myDorazio

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Nov 1, 2014
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Bought this 300 gallon wrap-aroound beauty for a lot--a lot for me. Shippers cracked the bottom. Like an idiot, I did not insure during shipping. Leaks at bottom. If I fix the links, does anyone know if it might shatter over time?

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The bottom is made of three pieces of 1/2 inch glass. The middle piece has two banana shaped cracks running about 14 inches to the back of the tank. The tank has a wooden apron running around it and is itself sitting on 1/2 solid teak based. In other words, if you lift the tank off the stand, it has 1/2 inch of solid wood base attached all around the bottom. So the tank sits on the 1/2 inch solid wood and the 1/2 inch solid wood sits on the base. I have attached a picture of the tank bottom. You can see a couple of extra pieces of glass have been siliconed over the crack that runs from the center to the upper right of the picture.

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I'm about to try to cover the bottom where the cracks are entirely with GE Type 1 silicon. And if that doesn't work I may get an above ground swimming pool liner and find an adhesive to adhere it to the entire bottom of the tank, basically to create a lining for this compromised tank.

So my question is, if I manage to stop the leak, and it holds without shattering catastrophically for, for example three days, then will it hold over time? My hope is that if it holds for a few days, then it will probably hold for 30 years. I can't see the bottom of the glass cracking any more because the weight of the water is supported by the wood underneath the glass, not the glass itself.

Does anyone know if a cracked glass bottom that has been made waterproof is at risk of just breaking out the wood underneath and shattering catastrophically?
 

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I would do the liner idea. Check with a local roofing contractor and see if you can get a piece of rubber roof. Seal the entire bottom with the GE then put the rubber on it. Just like adding another layer of film to a piece of safety glass.
 
I would do it. I have a 240 gal tank that also got a crack in its side and it will cost more money to replace the glass than it will to buy a new tank. In automobile terms, it is totalled. You don't want to risk filling up the tank with anything but solid pieces of glass, if you do this tarp idea and try to silicone the glass, it will burst because that will be a weak spot.

However, the ONLY thing I can think of, is if your crack is small enough, you could cut out the crack in a circle and use a bulkhead fitting to fill it and have that run to your sump.

But otherwise, your tank is compromised and 300 gallons breaking through the glass not only will hurt you severely if you are near by, but will also ruin your house

Sent from my SM-N900V using Aquarium Advice mobile app
 
Too true. In smaller tanks I have repaired bottom cracks that extended from side to side, by applying a large piece of glass that was several inches wide to cover the entire crack, situating the crack down the middle as much as possible.

I carefully smeared a thickish layer of silicone over the new glass, using a paint stirring stick to level the layer as much as I could. Placed it on the crack, which was supported underneath with wood, and gently pressed and slightly twisted the new glass piece down, much as you do when applying ceramic tile. I allowed the silicone to squeeze out all around, then smoothed the silicone over all the glass edges so that there would be no chance of either myself at some later date, or a fish, coming in contact with a sharp glass edge. This is on the inside, not the outside. I also put a bead of silicone over the crack on the outside and mushed it a bit flat, so it covered the crack well.

Because I feared the silicone sandwich would be a bit starved for air, I let it cure for a week before using it. So far, so good. Same basic idea has worked on side cracks too, in small tanks. Less than ten gallons. Since your tank has the support underneath, you might, possibly, get away with this kind of repair. I'd use half inch glass to make the repair with and let it cure for a couple of weeks. Edit.. just a piece of half inch glass is not cheap.. it gets very costly once you're past quarter inch thickness. And I'd want some kind of restraint around the circumference of the tank, at the bottom, a sort of giant band clamp or hose clamp, though how you'd get one that size I can't imagine. It might not look that great to have such a clamp, but would help fight sideways pressure. You don't just get pressure going downward, you also get pressure outward against the side glass. If you could find such a thing, might help.. this is just me thinking out of the box a bit, I'm not at all sure it could work.

And the risk is SO high. ONE gallon of water weighs a bit more than 8 pounds. 100 gallons is over 800 pounds, so your tank, full, would be in the neighbourhood of 2500 pounds of water, plus any rocks or gravel. It's an enormous amount of pressure that would be pretty catastrophic if it failed.

If you thought you wanted to try a fix, I'd want to move the tank to someplace else to do it. A storage locker maybe, or a garage. Somewhere so the water had a safe place to escape, maybe run down the driveway to a culvert or something of that sort. I'd make sure there was nothing that might be damaged by flying glass anywhere in the vicinity of the tank when it was test filled too.

I'd fill it with a hose from a good distance away, very, very slowly. If it held up for a few weeks, possibly, it might be ok. But stress over time might one day still result in a major disaster. But then you'd also lose all the fish, etc, as well.

It is truly a shame you didn't think to insure it, but how much will it cost you if it fails inside the house ? 2500 pounds of fishy water, the livestock, plants & rocks & gravel will all be exploding all over the place. Possibly flying glass shards could go in all directions too, maybe take out a window or a person ?

I really do feel your pain and I'd want to try and fix it too. But I fear the risks outweigh your chances of success.

Though I suspect it would cost as much as or even more than a new tank, I suppose you could try to have an acrylic liner made to fit inside it. You'd lose a bit of volume, but the overall appearance would be pretty much the same. Have to seal it somehow at the top so nothing could fall or work its way into the space between the glass and acrylic, cause you'd never be able to get it out.
 
Fixing something like glass to me is risky when weight is on it. You may think you have the entire crack covered but a hairline may exist past the patch area. Then when the weight of water and decor is added the glass on the bottom will stretch/stress at the crack extending it. Unless you are actually patching the ENTIRE bottom I wouldnt risk it.

I would personally go after the shippers. Did you inspect it on delivery, if you saw the crack I would have turned it away and made them pay for the repairs. Even a small claims would be better.

If you really want to repair it though I would either get a piece of glass or aquarium acrylic cut to the EXACT shape of the bottom (thats tough). then I would not even silicone the crack and just lay the new sheet over the old one and seal the edges. As another poster said you will STILL need a support under the tank because if that old glass is NOT sitting flush on something and raised off the base of whatever its on even an inch it will still eventually give. You could try as he said and use wood. Cut the wood to the EXACT shape of the glass and place it UNDER the thank to keep the glass from stressing.

I would take his advice as well and test this AWAY from your indoors. If its warm where you are leave the tank outside a few weeks filled and see if it holds up before committing to your indoors.
 
you say there is wooden base attached all the way around, is the entire bottom of the tank covered with the glass in direct contact with the wood or is it a frame around the bottom with gap between the actual glass plate and the stand/base?

If it is the first and the ENTIRE bottom plate is in contact with the base then you may be able to make it work. That way the wooden base is actually supporting the weight of the tank contents and not the glass plate itself.

If it is a frame and there is a gap under the plate, as in conventional "off the shelf" glass aquariums, the chance of a failure is much greater.

Personally I would only ever go acrylic on a tank that size with that many seams.
 
you say there is wooden base attached all the way around, is the entire bottom of the tank covered with the glass in direct contact with the wood or is it a frame around the bottom with gap between the actual glass plate and the stand/base?

If it is the first and the ENTIRE bottom plate is in contact with the base then you may be able to make it work. That way the wooden base is actually supporting the weight of the tank contents and not the glass plate itself.

If it is a frame and there is a gap under the plate, as in conventional "off the shelf" glass aquariums, the chance of a failure is much greater.

Personally I would only ever go acrylic on a tank that size with that many seams.

exactly even a 1/8" gap is too much stress on glass for anything you need to have the cracked sheet sandwiched TIGHT
 
The point about going after the shippers is a good one. Even though you did not insure it, they had an obligation to deliver the goods in usable condition. If you were unable to observe the crack due to the packing materials, I'd certainly contact the shippers and ask to submit a claim. If they refuse, take them to small claims court. It may be cheaper for them in the long run to satisfy your claim than to go to court. Court means a lot of time, possibly a lawyer and the risk they'll lose and have to pay anyway, though collecting a small claim can sometimes be a lot harder than winning a case.
You might get a lawyer to write the company demanding they make good on the damage if they refuse a claim as well.
Don't wait if you want to try this, there are often time limits imposed by law.
 
Sadly, if he didn't examine the cargo upon delivery and verify with the delivery person, it amounts to his word against theirs.
That is now greatly compounded by the fact that the tank has since delivery been filled and emptied of water and altered. Who's to say it didn't crack when first filled?
(not saying the OP is lying, just playing defense lawyer for the truck driver..LOL)
No shipping company would honor a claim without prior insurance under those circumstances.

Maybe try the seller of the tank?
Surely they have some type of warranty.
Delete this thread and start a new one about how it arrived perfect and then cracked when it got halfway full. ;)
 
weather you had bought ins or not the shipper is liable just a fyi
it wouldn't be for full value but a pro rated value maybe get $100.or so when its all said and done
each item shipped is covered under the shippers ins up to a certain amount the ins you didn't purchase would have covered the rest
 
weather you had bought ins or not the shipper is liable just a fyi
it wouldn't be for full value but a pro rated value maybe get $100.or so when its all said and done
each item shipped is covered under the shippers ins up to a certain amount the ins you didn't purchase would have covered the rest

that is true, same with the postal service, but the damage has to be documented at the time of delivery for something like this and at this point the tank has been filled and then altered (siliconed a patch).

The OP should have contacted both the manufacturer and the shipper immediately upon discovering the damage and not have proceeded the way they did.

so now we are at the point of figuring out a way to patch it.

someone mentioned using an acrylic patch, big no, no, silicone doesn't bond to acrylic anywhere near as strongly as it does to glass, the surface is too smooth. It would probably separate even in the best conditions.
 
At this point I would tear down the tank and replace that one (of three) pieces of glass. That's the only insurance that you have against a future break.
 
but I doubt it is rated for use in aquariums.
you would be best sticking with glass.
while acrylic is stronger, it is also more flexible and will transmit any flexing forces to the glass and possibly make matters worse in the long run. if you notice acrylic tanks do not have a bottom frame because the bottom plate would sag. Acrylic tanks should always be fully supported across the entire bottom.

you should use glass to patch glass and acrylic to patch acrylic.
 
Use glass with glass.
It won't shatter unless it's tough glass. Tough glass doesn't crack, tough glass shatters.

The hairline crack mentioned may be worth noting.
Is there a void below the tank?

All of my tanks have polystyrene protection on the base panel outside of the tank. So far so good.

As the glass isn't laminated I'd do like somebody else said.
One sheet fixed inside the tank covering the base panel, two pieces with a silicone bead will work if bracing gets in the way.
 
The only way to safely do it is to replace the bottom piece of glass. Anything else carries serious risk of catastrophic failure. 300g of water on your floor will destroy a house; think replacing drywall, flooring, insulation, and possibly even electronics and furniture. Then you have to take into account the loss of livestock. It's not worth the risk to save $200 by trying to patch the bottom of a tank.

Even if the bottom is fully supported, if it flexes at all the bottom would be toast.
 
The only way to safely do it is to replace the bottom piece of glass. Anything else carries serious risk of catastrophic failure. 300g of water on your floor will destroy a house; think replacing drywall, flooring, insulation, and possibly even electronics and furniture. Then you have to take into account the loss of livestock. It's not worth the risk to save $200 by trying to patch the bottom of a tank.

Even if the bottom is fully supported, if it flexes at all the bottom would be toast.

Strongly disagree with this statement!

My first tank I built, I dropped a rock into it which cracked the bottom, I patched it up just like this, when I emptied the tank during a full service there was a beautiful spider web mosaic of cracks running throughout the bottom panel.

Fortunately the base was twin skinned with laminate.
I refilled the tank and continued using it until the rear brace separated from the rear panel, again I was fortunate to use laminate glass as the panel simply bowed out, this time I shut the tank down. Definitely unsafe!

If the secondary piece of glass is complete with a sound silicone joint you will have no troubles what so ever.

If there is any flex on any tank it will give you the same trouble even if it was made by the best man in the best manufacturers in the entire world.

A fully supported bottom will not flex, if it does, it wasn't fully supported!

I personally would disregard this scaremongering.
(No offence mebbid but really I disagree 100% and I have a very good reason why)
One question to you, have you carried out this type of repair before or have you indulged yourself in tank construction?

I will say, the best way is to replace the bottom panel but it is not necessary.

My big tank is a twin skin design using regular glass, really I have no worries about the base panel on this build. (Vertical butt & inlay panel, similar to the ops suggested repair using a full sheet, I think it will have a lateral butt joint though as this is most common on manufactured tanks)
My reef tank is a twin skin base on the main display/sump section.
The remainder of my builds use laminate but the actual method of fixing varies, I still use silicone but some joints are vertical butts and some are lateral butts, neither is cause for concern but I think the lateral type joint offers an extra degree of security on the bottom piece.

These are my DIY. Designed and built by me, my first tank and the big tank I had a company manufacture the panels to spec (my bosses at the time)
The remainder I cut/drilled/polished myself.
 
Strongly disagree with this statement!

My first tank I built, I dropped a rock into it which cracked the bottom, I patched it up just like this, when I emptied the tank during a full service there was a beautiful spider web mosaic of cracks running throughout the bottom panel.

Fortunately the base was twin skinned with laminate.
I refilled the tank and continued using it until the rear brace separated from the rear panel, again I was fortunate to use laminate glass as the panel simply bowed out, this time I shut the tank down. Definitely unsafe!

If the secondary piece of glass is complete with a sound silicone joint you will have no troubles what so ever.

If there is any flex on any tank it will give you the same trouble even if it was made by the best man in the best manufacturers in the entire world.

A fully supported bottom will not flex, if it does, it wasn't fully supported!

I personally would disregard this scaremongering.
(No offence mebbid but really I disagree 100% and I have a very good reason why)
One question to you, have you carried out this type of repair before or have you indulged yourself in tank construction?

I will say, the best way is to replace the bottom panel but it is not necessary.

My big tank is a twin skin design using regular glass, really I have no worries about the base panel on this build. (Vertical butt & inlay panel, similar to the ops suggested repair using a full sheet, I think it will have a lateral butt joint though as this is most common on manufactured tanks)
My reef tank is a twin skin base on the main display/sump section.
The remainder of my builds use laminate but the actual method of fixing varies, I still use silicone but some joints are vertical butts and some are lateral butts, neither is cause for concern but I think the lateral type joint offers an extra degree of security on the bottom piece.

These are my DIY. Designed and built by me, my first tank and the big tank I had a company manufacture the panels to spec (my bosses at the time)
The remainder I cut/drilled/polished myself.
Thats funny, because I strongly disagree with this statement. Like I said before, is it worth it to risk thousands of dollars in damage to save $200? Sounds like a pretty cut and dry trade off to me.
 
Have you carried out any type of work of this nature?
Do you have any glass experience? (Cutting, fitting etc)
Do you have any silicone glass experience? (E.g. Tough walls, shop fronts etc.)

I agree the best way would be to replace the panel, BUT! It is NOT the disaster you allude to should it be left in place.

Either way you are paying for a full sheet of glass! Where is the saving? Labor!

Your time or somebody else's. No money is saved. I state this on the assumption all works are of DIY nature and no contractors are involved.

If you're paying somebody else, start again, if you're doing it, tape the base externally, support tank on polystyrene in situ, level tank, install replacement panel, silicone joint perimeter.

Allow product to fully cure!

Test fill with water to 33%, check for leaks.
50% check.
Fill check.

Have hose handy to siphon should you need to.

If you are confident in your work, this type of repair will present no real problems. The most difficult task will be getting the sheet in the tank. Cut a card or better still plywood template, trial run it, if it goes in and out, take that to a glass merchant, have a panel cut and polished, repeat the above but for real.
 
I agree the best way would be to replace the panel, BUT! It is NOT the disaster you allude to should it be left in place.

No, I don't have glass work experience. Nor do I need glass experience to see the potential problems that arise from trying to patch a crack rather than replace the pane of glass.

You said it yourself that the cracked glass you patched was toast with a mosaic of cracks running through it.

My point is, that even if the chance of the bottom panel breaking is minute, the $200 ish dollars that it will cost you to buy a new panel of glass and replace it is miniscule compared to what could happen IF that failure were to happen.

Even assuming all repairs would be diy the damage to your house could EASILY cost thousands of dollars in damage.

There was a person on this forum that bought a cheap stand that got wet and failed dumping a 55g tank on the floor. If i remember correctly the repair bill was over $10,000.

The risk of patching outweighs the benefit.
 
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