you will need:
aquarium sealer or (i reccommend) 100% silicone caulk. this can be found at any hardware store
a caulk gun
razor scraper
knife
white vinegar
round peice of plastic (margarine tub lids work best)
scissors
small round object (penny works best)
pencil
sponge
paper towels
bucket of water

empty and clean the tank thoroughly. if the tank was in use, place the gravel with tank water covering it in a bucket. do not clean the gravel, you will remove the beneficial bacteria that is living in the gravel. you can use this to restart the tank. make sure that the tank water covers the gravel by about an inch. also if you can reserve as much of the water as possible.

determine at what joint your leak is at and with the razor scraper and knife remove as much of the silicone as you can. try not to get too deep between the two panes of glass. you will need to have ventilation at this point of the repair. with the white vinegar and a sponge, clean the area trying not to get the vinegar on the silicone on the other joints. the vinegar is an acid and will remove the residue left by the old sealer. wipe up any extra vinegar and again rinse the tank in hot water several times to ensure that the vinegar is thoroughly removed. let the tank completely dry for about 1-2 hours.

you will need to make a spreader with the margarine tub lid. clean the lid in hot water to remove any food particles. let dry. with your scissors cut the edge of the lid off. cut the lid in half and in half again. at the pointy end, place the penny to give a curve about a 1/3" from the end. mark the curve and cut.

if you are using silicone make sure that it is 100% silicone and clear. additives can leach harmful elements into your tank causing fish loss. with either the aquarium sealer or the silicone in a caulk gun, run a bead of silicone from one end of the repair to the other. take the spreader that you made and with the sides against the glass of the tank, run this along the bead of caulk. you will want to press the spreader into the silicone to remove any air bubbles and get a good seal. the spreader will also remove the excess caulk. you can also use your finger, but this is messier. wet your finger and pressing firmly run along the bead of caulk. wipe away any excess caulk with the paper towels.

you will need to let the caulk or sealer cure for 72 hours. after this time, rinse the tank thoroughly and check for leaks. if there are no leaks you can refill the tank with the reserved water and gravel. if you do detect leaks you might have an air bubble which has left a hole in the repair. if so, you will need to repeat the process again.

jas i said i have used this method to repair many tanks, including replacing a broken peice of glass in two of them.

i have a small peice of glass missng right in the corner of my tank, the same size roughly as a quarter of a five pence piece, do i do the same process as the vinegar might burn the silicone that is there already
thanks
fishatron

I picked up a tank a long time ago and it leaked. My intentions were to strip the tank down and rebuild. Ive discovered that Im havein a hard time removing some of the sealant. Its been put on very thickly in some places. Any tips would be appreciated. Ive used a blade but its really stuck on there. Please help

Nevermind, Ive now removed the sealant with just brute strenght, luckly I didnt break any glass.

Thanks Semper, great info

ahh i was told that you cant do this!!!!!! I know a guy in Germany who builds tanks and he warned me not to reseal.
I a juwel 180 tank that has split the seal between the front and the bottom. LOL 46 gallons of water on my livingroom floor. didnt loose a fish though. i and usually quite handy and am well up to have a try.
Do you guys really think its worth having a go, my carpets are not good swimmers, so i cant afford a problem.

The vinegar won't burn the silicone, it simply removes any residue left behind in the removal procedure outlined earlier, so you've no worries on that score.

my tank split for about 5 or 6 inches will i need to remove the silicone from between the panels of glass to get a good seal?

Thanks for posting this. I picked up a tank my neighbours were chucking out, seams seemed okay but since I've gotten it home I've realized I will need to fix at least one seam.

As well, there is a crack in the upper right corner near the top bracing, it's curved and is about half an inch down. Can I put sealant on this crack as well to ensure that water can't or won't slosh out of it there? (I wouldn't fill the tank up to the top with this crack, but I'd like to seal it and be sure anyways) Or is it best to replace the glass?

You would be better off replacing the panel. Once the crack has appeared, it will continue to "run" when subjected to the slightest pressure. Better be safe than have a wet carpet.

Thank you for your reply Windsor-Aquatic. I have taken the whole tank apart and discovered a chip in the glass as well as the initial crack/curve.

The glass is now all clean of any dirt and silicone, and my plans are to cut the glass down and build a custom betta tank. It should be cool. I hope. Being a girl and *somewhat handy* but not really having the confidence to do this,since I've never done it before, I really hope it works out!!! I will post pics even if it turns out like crap.

Wish me luck!! ( I just keep telling myself it was free, they were chucking it, who cares if I totally demolish it...)

When I was taking it apart though, I noticed silicone in between the panes of glass. Do I need to line the glass before putting it together or will this squirt in between as I am assembling it?? I think that is my only question for now...

When you make it, put a line of silicone on one of the two faces that will butt together; assemble each panel of glass in turn, and wipe away any excess silicone that squeezes out immediately. Any that you miss can be removed later, once it has cured, using a new stanley/craft blade.

best of luck!!! LMK



lol nice post!

hi i resealed my tank in the ways mentioned above the only difference was i found that vinegar wasnt very good at removing the residue so i got some rubbing alcohol from ebay it removed every last trace and because it evaporates it leaves no residue behind on the glass.

To be honest, every tank i've ever had that developed a problem like this, was put into storage for future as a vivarium/terrarium etc. and a new tank bought. It just eases worries, and the camping/sealing process used by most manufacturers gives a pretty damn reliable result.

I have moldy silicon all along all 4 corners of the inside of the tank. I had the tank given to me and I would like to put use to it. I want to re-do the siliconing but i am going into this blind, I have not done this before. Do i just need to scrape the inner layer out and put new stuff in..without breaking apart the panels of glass. There are no cracks or breaks whats-so-ever, just moldy silicon.

yep thats it! if you want to go the whole hog, and rebuild your tank, ok. but this will do the job if you have no leaks after you have taken out the old silicone. fill the tank half way with tap water, if it has no leaks, empty it dry it re silicone the seal and off you go.

urgent ===i have a 75 gallon tall tank and i resealed it tested it and it was perfect. i put it in place and filled it with water i left it alone for 2 days and one night it started to leak in a corner first a little squirt and then started to spray like crazy. i empyed it and wondering if i need to reseal it again. it looks like the bottom corner has a big chip in it. if i reseal it and add a lot of silicone to that corner will it hold???