Repairing Cracked Tank

[jewett]

I left a 29 gallon tank outside a few winters ago and surprise surprise the bottom sheet of glass cracked. I have held on to it in the hopes I can repair it. I'm thinking of purchasing a sheet of glass from the local DIY store and siliconing it to the inside. Is this likely to work? The store I went to only has glass that is 1/8 inch thickness - I would prefer 1/4", but does it matter? I use no substrate in my tanks so the only weight would be water, but its not like water is all the light anyway... Or should I forgo glass and use plexi?
Any thoughts? The crack is pretty well branched over the whole bottom, but all the pieces are still in tact. In fact, its made kind of a pretty pattern
Thank!
Heather

 

[Azhael]

I can´t help you with the adequate thickness of the glass, but i can tell you that rather than placing a new sheet over the broken one, i´d remove the entire floor, remove the old silicone and then put a new replacement sheet with new silicone. You need a new sheet of glass anyway...

 

[jewett]

Is there a tool that is made specifically for removing silicone? Or should I just use a box cutter type blade? I can be rather inept and dismantling an aquarium could be super easy, but I am pretty sure I have just the right mix of talent and skill to break large pieces of glass and then cut myself... I can add the scar to my collection. My appendages are already like a monument to the cool injuries that can be sustained by doing stupid things, or sometimes the right things done badly...

 

[Azhael]

I´m no stranger to flesh badges for clumsiness, but i don´t think you´ll have a problem with the silicone. A regular razor (a box cutter blade is perfect) is all you need. I would start by cracking the broken sheet into pieces so that you can (with gloves or medieval armour) push on the attached bits and stretch the silicone a bit and get the tip of the razor in. Once the first insition is made it gets easier. After that just scratch the remainding silicone with the razor and scrub the area with some soap to get rid of any bits. That should leave the glass in your tank perfectly clean and ready to be siliconed again.

 

[jewett]

Thank you so much, Azhael! I have tomorrow off from work, so I just may have a little project for myself to occupy the day (screw holiday shopping - Christmas is still weeks away!)

Heather

 

[Greatwtehunter]

Repairing the bottom glass is tricky, to say the least. In most tanks, that sides are sat on top of the bottom pane then siliconed together. If this is the case then your best option is to take off the bottom trim and replace the pane from the bottom. If the side pieces are siliconed around the bottom pane then all you have to do is remove the top trim piece and drop a new piece in.

They do make tools designed for removing silicone. They look like this or this. I got mine from Lowes, or maybe it was Wal-mart.

 

[jewett]

Thanks for that information Justin. I need to remove the cracked bottom to see just what I am dealing with.
Heather

 

[SludgeMunkey]

Skip the acrylic as a replacement panel. You would have to use a minimum of 3/8 thick for aquatic use and it will still fail in time due to the flexible nature of the plastic.

For glass, you must use a minimum of .25 inch tempered glass, cut to exact size. Anything thinner /and or non tempered will not support the weight of water.

A really easy option I use is to leave the cracked bottom in place. I invert the tank, seal the crack with a very thin layer of silicone and let it cure. Then I just fill the entire tank bottom exterior with two part water proof epoxy. Just make sure the tank is level and secure before pouring the epoxy.

Let it cure, leak test in a suitable place with full volume water for 48 hours, and then return it to service if there are no drips.


I have very poor coarse motor skills these days and drop a lot of rocks, can you tell?:blob:

 

[jewett]

THAT sounds like something I can do, Johnny. Thank you so much for the ideas. Glad I was lazy enough today to not try taking the bottom out, yet. If I go to Lowes or The Home Depot and ask for water proof epoxy will they be able to send me in the right direction ( ie its common stuff?)
Heather

 

[SludgeMunkey]

Yeah, it is really common. Truthfully, it doesn't even have to be waterproof or aquaculture rated since you seal the cracks with silicone and it is outside the tank. The epoxy is more of a structural integrity type of addition. Think of it as a super reinforced bottom. You could conceivably use auto body fiberglass too, but that is too much like work.

Three things I forgot to mention earlier:

You can paint the outside exterior of the tank after the silicone, if you want an easy clean substrate-less type bottom.

If, during the leak test, it fails and you want to try the repair again, you can easily remove the epoxy by carefully heating it with a hair dryer and peeling it off in chunks.

Epoxy can stink as it cures, so use a five or fifteen minute type, just remember to mix it right and give it extra cure time at lower than room temperatures.

 

[Jennewt]

Another option would be to patch the crack with silicone, and then use the tank for a terrarium. I think any repair is somewhat risky if you are planning to put water in it.