Bottom of 180 gal cracked...

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biguebs

Aquarium Advice Apprentice
Joined
Jun 3, 2011
Messages
13
So, a week or so the bottom of my 180 gal tank (6' x 2' footprint) cracked from the front to the back. Luckily, it didn't explode and I was able to get the fish out and drain the rest of the water with only about 20 gal or so of water seeping out onto the floor.

Anyway, I have posted on another forum without any response, was hoping someone on this site could help me. I have read that there are basically two options for me here: 1) remove the old cracked bottom/old silicone and replace that glass piece, silicone it on and silicone inside seams 2) get a piece of glass cut that will fit just inside the tank and on top of the cracked piece, silicone the inside seams.

I have also read several threads where people have just said to scrap the tank because fixing it is too risky? Anyone with experience doing this on a large tank like this that could point me in the correct/"easier" direction?
 
Sorry to hear about this .... thankfully you saved the fish and limited the water loss. Unless you can it professionally fixed for the cost of a new one, I'm going to say get a new tank. I'd consider a cracked glass tank structurally compromised.
 
you could definately try to replace the bottom of it yourself, or bring it to a glass place and maybe they could do it for you (make sure they use the right silicone)? I honestly have no idea of cost though and it just may be cheaper finding a new 180 tank
 
I would also figure out why it cracked. Whether you fix it or get a new one, you dont want to repeat that mess. I have heard this happening with tanks that are put on a styrofoam pad or something else rather than directly on the stand. Did you have a rock that the point was pushing on the bottom of the tank? I line the bottom of my tanks with eggcrate to avoid pressure spots.
 
I had a cracked 20 gal I think it was or 30 cant remember, several years ago.... I replaced it with a freebie tank I found that didnt hold water. I was able to replace and re did all the seals. That was a small tank tho. Not to sure on the big tank. If you would leave the cracked glass in and lay another on top, I am not sure how that would work. Was the crack due to something being dropped or like a stress crack, for lack of better words? if it was the latter without fixing the cause, it may happen again, if that makes sense. Try craigslist? ive had great luck with it. i got a 140 SW set up that was used 8 months for $300... sold the lighting and sw stuff and it paid for my tank and then some. That was my best find by far! but they needed it GONE NOW!!!
 
I think your only real option is to rebuild the tank with a new bottom piece and the old sides. I would be very reluctant to just silicone a 'new bottom' over the old one. I think that is a disaster waiting to re-happen. There is a reason the bottom cracked and a quickie patch job on a 180 gallon tank will likely only compound your problem.
 
Thanks for your responses all. Just to clarify, I wasn't talking about patching up over the crack with a smaller piece of glass, it was going to be the whole 6' x 2' minus the 1/2" for the glass on all sides.

I really think I'm going to just replace the whole bottom end. And I believe the cause of the crack was a stress crack, I don't think my stand was exactly level and it created a pressure point (I will obviously address this prior to setting the tank up again). Also, I didn't have the plastic framing on the bottom and I think this may have contributed to the issue. I ordered a new frame.

Is there anyone who has replaced the bottom of a large tank like this before? I was hoping to draw from someone else's experience?
 
Thanks for your responses all. Just to clarify, I wasn't talking about patching up over the crack with a smaller piece of glass, it was going to be the whole 6' x 2' minus the 1/2" for the glass on all sides.

I understand your intentions and think that is a very, very bad idea. There is information on the net about building / rebuilding a tank. Here is something I found quickly, but you can find plenty more if you look around.

YouTube - ‪Rickets Reef: DIY HowTo Make A Glass Aquarium in 3 Steps...‬‏
 
I understand your intentions and think that is a very, very bad idea. There is information on the net about building / rebuilding a tank. Here is something I found quickly, but you can find plenty more if you look around.

YouTube - ‪Rickets Reef: DIY HowTo Make A Glass Aquarium in 3 Steps...‬‏


I had read that it was a "standard way" to fix a broken bottom with one large crack on some other forum, and to be honest it sounded sketchy to me as well! I am going to attempt to remove and replace the bottom pane with some 1/2" tempered glass, attach the frame on the bottom, and hope for the best... now I just need to call the glass shop. Anyone have an idea on a price for a piece of glass like that? I guess I'll find out
 
Tempered glass that size isn't gonna be cheap, might cost the price of the tank and since the bottom cracked and didn't explode means it was standard glass anyways. You could look into a piece of laminated glass, but the split sheet won't have the same tensile strength as a single sheet of the same thickness.

The other thing you need to watch is compromising the seams of the 4 side panels. Any flex while removing/installing the bottom and the silicone seal can be weakened/separated IMO/E. I'd suggest a complete reseal of all 5 pieces while you have it apart.

Good luck!
 
i always see people making tanks out of plywood. maybe you could seal a piece of plywood like you would if you were making a plywood tank. ive seen really thick plexiglass at homedepot or lowes idk if you can get a piece that large tho but its worth a shot.
 
i would just run a bead of 100% silicon over the crack and run your finger over it and repeat this a few times...wait 24 hours and test it

That won't work.

Best way to do this is to replace the glass, I just crack my 20 long the side, what I did was took one of my old 10 gallon n cut it into side. Redo the whole tank.

A good way to do is make a box the same size the tank is without the frame.
Install all 5 glass into the box n seal the inside. This way when ur done, slowing just pull out the box n there u go a repair tank, add the frame more seal n ur done.
 
I was talking to someone about this at the LFS, they said they once fixed their 220 gal with a similar crack by sealing the crack w/silicone and then getting a piece of 3/4" plywood and and sticking it under the cracked glass to provide the necessary support. Then they put some 1/2" extruded styrofoam from lowes between the plywood and the stand. Anyone ever heard of an approach like that?
 
I would just put a new (smaller) piece in over the old and silicone it in. I have seen this done numerous times locally and they all held water just fine. It really is more common than a lot of people think. Only pain is taking the top trim off so u can get the new glass in.
 
I would just put a new (smaller) piece in over the old and silicone it in. I have seen this done numerous times locally and they all held water just fine. It really is more common than a lot of people think. Only pain is taking the top trim off so u can get the new glass in.

How small of a piece do you mean? And what kind of glass?
 
I've never done it personally but from what I've heard you just get the same size piece minus the width of the glass. I'm not sure what type of glass to use with a tank that size.
 
If it was my tank I would get a piece of glass about 6 to 8" wide, enough to cover the crack and silicone it in . I would not replace the bottom frame but would set it on a layer of styro. The local Big Al's has a shark tank that is 4' x 8' x 3' tall that has a cracked bottom that was repaired with a patch. the tank holds in excess of 700gallons. Somewhere on the net is a pictorial story about the building of a 16 ' long tank that has 3 pieces for the bottom.
 
I just bought a 250 gallon tank that was cracked along the bottom. what i did was get a custom peice of tempered glass allready drilled where the overflow and return were and cyliconed it right on top of the cracked glass. i also put a bead of cylicone along the crack.only hard part scraping the old cylicone off along the bottom that sucked because it was such a big tank.
 
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