300 gal Crack and silicon repair, help please.

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Tokay

Candiru
MFK Member
Apr 22, 2006
167
3
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Just picked up this 300 gallon(8'X24"tallX30”wide) glass aquarium the other day, sadly it obtain a crack during transpiration. The bottom of the tank is made out of two pieces of 1/2 glass, each with 4 large 3-4" holes for bulkheads in the two overflow boxes. It also is trimmed along the inside of the bottom of the tank with 3" wide 1/2" glass. The top layer of the bottom glass has a crack that starts at the edge and curves thru the middle. There is a second crack that seems to be in the second layer and curves. I have highlighted the cracks in one picture. The crack is smooth the touch.

Aquarium has a double layer bottom, two glass overflows with 2 3-4" holes in each box, 3" glass trimming the inside of the tank and top, the 5 glass braces along the top are made of two strips of glass, and the top corners have triangular pieces at the top. It is sitting on a wood frame that I am going to reinforce and eventually trim and support the entire tank.

I have to get this tank up and running for my 26" silver aro and 18" RT/SN catfish. I have been asking around for idea and looking for a way to fix the aquarium and not be force to trash the tank. So far I have received three different ideas from people.

1. Place a large peace of glass over the crack in the tank and silicon it down. Even over the entire bottom of the tank, but it would be hard because of the overflows, and 3" trimming. Silicon the panel down, and give the tank a wood or metal framing around the top and bottom for extra support.

2. Someone told me that i could try fiber glassing the entire bottom of the tank. I don’t know if fiberglass works well with glass. If possible i wonder if i can fiberglass over silicon, get the fiber to cover the bottom and the edge trimming with a water tight seal, and if i could transport the tank after the fiberglass has been tested outside without messing up the fiberglass.

3. A friend said i should replace both glass bottom layers. Im not sure how much two 8X2' 1/2 thick sheets of glass with 4 large holes drilled in would cost, but prob a lot more then what i paid for the tank and stand. Deconstruction and construction would be a big job, I have never took up a tank this large before.

Lastly what brand and type of silicon do you large fish tank owners/builders use on ur large tanks? Whatever i end up doing, im planning to resilicon the entire tank. So i will need large amounts of silicon, hopefully it comes in the tubes that fit in cocking guys. I heard of brands I can find at hardware stores but I want to make sure I get the best for aquariums and also in large amounts. I know to remove all the old silicon and use rubbing alcohol to clean the area. Since there is so many pieces of glass on this tank i prob would not be able to do it all at once, one section at a time.

Any information would help, and gladly appreciated. Anyone that sells glass or silicon feel free to contact me. Thank you for your time. MFK for life!

The aquarium
300001.jpg



The overflow and trimming along inside of the tank.
300011.jpg


Crack
300008.jpg


Crack
300007.jpg


Chip, it is either from the crack or caused it.
300009.jpg
 
That is a huge tank. I wouldn't use it unless the bottom was replaced... and one thick sheet of glass is better than two thinner sheets.... plus would save some weight (two half inch sheets is NOT as strong as one one inch thick piece)

I see there is no bottom frame, so it might be possible to replace the bottom with out fully dismantling the sides..
 
Yeah, a third sheet a glass should work...
 
Just to be clear the red line is the crack and only goes to one side (not across the glass).

If so, and you can't afford a new bottom (check commercial building salvage yards, they strip buildings of all the good stuff before a demo.) get the largest piece of glass that fits in the bottom without overlapping the overflows. remove the old silicone and clean up. The glass has to be perfectly clean when you sandwich the two together.

Now for the good news...You have to silicone the whole tank at once. Silicone doesn't sick to itself after it's cured.

To make it easier, you can get an electric caulking gun http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94849

or air powered if you have a compressor http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95431

Look for johnptc's posts http://www.monsterfishkeepers.com/forums/showthread.php?t=118131&highlight=silicone

Dr Joe

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thank you everyone that has posted a comment so far. Of all the idea so far, the best would be to take my time to buy a new bottom layer of about 1" thick glass . It would be the only respectable thing to do for my silver at this size. If im going to keep it for as long as i live, id have to go big on the tank and filtration. Im searching for any source of glass fish tank builders, for the glass.
 
umm if i were you id go to a aquariums builder tell them can u please rip this tank apart and rebuild it and use a new base orrrr do it urself but it would be hard top replace the base. if i were u get it done by a pro or get a new tank i mean just removing panels is a pain and can get srsly nasty. another thing is to just remove all panels remove all silicone buy a ew 12mm base add floor bracing and use ge scs-1200
 
Anyone know a source for glass? I know of a few tank building companies but they deal with acrylic. Trying to find a glass aquarium company local to sourthern CA. Since i have to silicon the entire tank at once its going to be a huge mission. Just taking it apart is going to be a huge task. But once i find my new bottom layer of glass and ready to start siliconing back together. Should i build a wood frame to hold the tank together as it is being glued and as it cures? I figured something has to hold it in place while i work around it. And should i assume ge scs-1200 is the best silicon to use? does the brand matter on quality?
 
I bought a 300 with a Y crack in one of the three bottom panels. Taking it apart was not an option seeing as it has 3" angle welded around the entire tank and also serves as the stand. I ordered a piece of 1/2" 32x23 3/4 so the new panel overlapped the next bottom panel. The tank is 3/4" glass, just if anyone was wondering. I used an entire tube of all-glass silicone and was sure to do the underneath as well. It has been holding for 6 months and i have faith in it. Your situation might be better to leave it to a pro, but if your feeling frisky and looking to save some $$$ you could try yourself. It is quite the task.
 
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