Cracked glass

[taker101]

I recently acquired a 45 gal tank with a crack on the bottom glass. What I'm wondering is if I can repair the existing glass and have it be strong enough to not crack in that panel again


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[BillD]

Not knowing the exact nature of the crack, it is difficult to say how it would be best repaired. A patch may work fine, or a patch on both sides, inside and out, or perhaps a new bottom placed inside the tank might be a better solution. Of course, you can remove the bottom and replace it as well. I personally have no qualms about patching a tank.

 

[PB_Smith]

repairing a cracked bottom plate is not going to work, at least not reliably.
Replacing the bottom plate requires taking the tank apart, buying the glass (tempered, twice the thickness of the side panels) and getting it all back together again.

In my mind it may be easier/less expensive or almost the same cost to just purchase a new tank.

 

[BillD]

repairing a cracked bottom plate is not going to work, at least not reliably.
Replacing the bottom plate requires taking the tank apart, buying the glass (tempered, twice the thickness of the side panels) and getting it all back together again.

In my mind it may be easier/less expensive or almost the same cost to just purchase a new tank.

Sorry, this isn't true. The bottom pane doesn't need to be tempered, nor does it need to be thicker. In fact the opposite is true in terms of thickness if you use tempered glass. As well the tank doesn't need to be taken apart to replace the bottom. It can be fixed reliably in in most cases with a patch. The local Big Al's has a 740 gal tank with a patch on the bottom. It has been patched for many years.

 

[PB_Smith]

Sorry, this isn't true. The bottom pane doesn't need to be tempered, nor does it need to be thicker. In fact the opposite is true in terms of thickness if you use tempered glass. As well the tank doesn't need to be taken apart to replace the bottom. It can be fixed reliably in in most cases with a patch. The local Big Al's has a 740 gal tank with a patch on the bottom. It has been patched for many years.

You are generally correct, but even though you do not have to take every panel apart, it is still a major undertaking to remove/replace the bottom plate, even more so if there is a frame attached....
so let's just say we are both right.

It also really depends on where, how long, and what direction of the crack as to whether or not a patch will hold.
If it is a crack in a corner or something, sure I can see a patch working, but if the crack bisects the middle portion of the plate, I simply wouldn't risk it failing.
Also an incomplete crack will continue to run, putting a patch on it will do absolutely nothing to prevent that. The only way to fix it is to go through the trouble of drilling the crack, patching it, etc. like is done with car windshields, only problem is most tanks use tempered glass for the bottom and tempered can't be drilled, at least not by most hobbyist.

Not knowing the specifics of the tank in question, I opted for giving the "safe" answer.

If it were a 740 gallon tank then the impetus too patch it would be considerably greater, but a 40-50 gallon tank can be had anywhere and rather inexpensively.

Whenever you consider things like craigs list, Petco $1-a-gallon sales, etc., etc. and how much the OP's time is worth, it quickly becomes easy to see that in the long run it would be cheaper and safer to simply purchase another tank.

 

[BillD]

Whether an incomplete crack will run is debatable. I have a tank like that I patched about 5 years ago, and the crack has not grown. It isn't on the bottom, but the back where there is flexing. Of course, buying a new tank is an option. Whether it is inexpensive is a relative thing. Not everyone has the coin to scrap an otherwise good tank and buy a new one. Most of my tanks were bought as leakers, very inexpensively. It took some time to repair them, for sure, but the total outlay was very small. I love people who can afford to pitch tanks because of a little leak.
Keep in mind also that new tanks sometimes leak, shortly after purchase. Most of my leakers were tanks returned to the store under warranty.
I will agree that sometimes the cost makes repair prohibitive.

 

[PB_Smith]

I will agree that sometimes the cost makes repair prohibitive.

I agree, and I am certainly well within the category of "can't afford to just buy a new one", but I was considering the cost of the glass if replacing the bottom, silicone and then the time/labor involved and the Op would easily be at or above the $50-$60 I'm sure he could get another tank for.

If it were a larger tank then for sure it would be worth it to try to patch it, but a tank the size of the OP's just all around doesn't seem worth it in my eyes, unless of course it is a minor crack in a corner or similar.

A picture would help immensely in providing good, specific advice.

 

[BillD]

I can't argue with the need to look at cost versus benefit. If you have to buy a large piece of glass, it will likely be cost prohibitive. I happen to have some pieces of 3/16" and 1/4" glass lying around that allow me to eliminate that from the equation. What I don't have is thicker glass for larger tanks. I do know someone who does though, and silicone is cheap.

 

[PB_Smith]

I have found that the pre-cut pieces of glass and acrylic/plastic for picture frames at Home Depot to be perfect for small repairs and only cost a few $$ at most.




OH YEAH!!!
VERY IMPORTANT!
To the OP, if you do attempt to patch it, all patching MUST be done on the inside of the tank, especially any bottom patches.
That way you are utilizing the water pressure to hold it against the glass.
If patched on the outside of the tank, that same water pressure will be applied to pushing the patch off the glass.

 

[Ricky 1]

Perhaps a photo of the crack would give us a better idea, is this possible T........

 

[taker101]

I will take a pic of crack when i get home


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[PB_Smith]

The styro can be painted with latex paint or probably even craft paint. Only the visible edges need to be done.
Andy has covered point loads from outside the tank, but, they can occur inside the tank as well. A rock sitting on a single grain of gravel can bust the bottom (a friend lost two this way). The very first all glass tanks, which originated in my home town in 1957, were built like the one in the picture, with no trim. After numerous broken bottoms from people setting the tank on a grain of gravel, a frame was added to lift the bottom.
I am a big fan of styro under tanks. However, it must be noted that styro will not help with level. It will aid with uneven surfaces, or those that aren't perfectly flat. Contrary to what is often stated on forums, it will also add support to the bottom glass, if there is no frame as in the tank in question, just as it does with an acrylic tank.

after having a wet rock slip from my grasp and hit the bottom and hearing that distinct TINK! sound of cracking glass many, many years ago, I have always used something in the bottom of the tank if it's glass. Whether it be an undergravel filter plate, eggcrate, or sheet of corrugated plastic (my new fav), that way when I drop something the bottom is protected.

 

[Ricky 1]

lets wait till we get a photo guys, I was in the glass trade, we need to see it first, so we can evaluate it.........

 

[jrc0528]

Is it possible for tempered glass to crack? Wouldn't it just shatter instead?

 

[MeCasa]

Thick glass can get expensive but you already have a layer so just have local hardware store cut an 1/8" piece ($10) 1/8" smaller than tank, lightly sand edges with sanding block (doesn't crack as easy) buy two tubes of silicone ($12)

Clean bottom of tank first with water and cleaner then with solvent, remove old silicone down even with bottom of tank using razor scraper ($4), apply silicone liberally but evenly across bottom of tank, throw in new glass, work in in, then make a pretty bead on outside

Better than new and it took less time to fix then it did talking about fixing

 

[Brookster123]

Is it possible for tempered glass to crack? Wouldn't it just shatter instead?

It can crack, i cracked a new 40 breeder which said the glass was tempered. If you hit it with a hammer it should shatter into lots of small pieces vs. Jagged plates and shards.

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[taker101]

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[taker101]

Also i need to know what silicone is aquarium safe to repair the damage


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[Tolak]

You also have to think if the risk of 45 gallons worth of water damage is less than the money saved repairing. All my tanks are in the basement, concrete floor, floor drain. It would be save the fish & mop the floor with a bit of bleach, so cost effective here.

If this tank is in a finished area, carpeted & such, especially with living areas below it, well, time to make a call to the homeowners insurance. Years back when 5 gallon drinking water jugs were made of glass I saw one fall & shatter on a concrete loading dock. Instant 30' puddle, pretty impressive, nothing but wet concrete & some busted glass as far as damage. A residential incident could get pretty involved as far as clean up.

 

[taker101]

My tank is gonna be located in the basement as well so no worries there


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