Possiblly resealing a 55 gallon tank..advice


Hey everybody,

Ive made some threads about this long story short, my school science teacher has some fish tanks he needs gone, im going to get a tank which is 1.495metres/ 58.85 inches long, 31cm/12.2inches wide and 45cm/17.7inches deep. 205 litres/55gallons. (note, when measured the depth could have been done wrong but its around that height, ill be checking tommorrow at school )

It was used to house turtles but idk how long its been since its had fish or turtles as i wasnt at the school when it was used. Ill ask the teacher tommorrow to see but idk what he can tell me, i found out that if they fill the tank half way up for the turtle to have a place to get onto land its possible the top half of tank silicone is cracked, ill put water in the tank for 1 week to test leaking but it could be a rather old tank so i'm thinking i should reseal with silicone. Its glass btw. I believe this was a custom tank the teacher made from specially cut glass and he did the silicone job himself, ill have to check on that though.

Anyway, do you guys have any tips and thoughts on resealing the tank??? i plan to use it to keep African or American Cichlids.

Thanks for all your help,

Peter :)


Hey PeterFishKeepin,
I know I seem to have an opinion on everything but in this case I do have many years experience working with glass and Australian silicone. In my last 25 years as a construction worker it was my daily life.

So I have cut glass and been cut by it. I have used thousands of cartilages of silicone.

Sorry but I can’t be bothered resealing my own tanks from the rubbish dump. I get tanks for $10 Australian per foot , including all the filters ,heaters , pink gravel and medications you can think of. Apart from the cost of each tube of construction grade silicone I know the work and time involved. It’s a lot of work to clean every last bit of silicone off glass . Multiple new razor blades are required to get ALL the old silicone off. New silicone will not stick properly to any old silicone. Even the smallest of residues is enough to make the new silicone not get a full bold.

Now a point of concern.
Up to a ten gallon /50 litre tank you can use cheap silicone from Bunnings. It’s still around $15 a tube.
Any tank over that size requires structural grade silicone. It’s more expensive and has a short shelf life . Bunnings don’t sell it. You can get it from a glass workshops. Perhaps for boxes of beer? If you can talk to the tradesmen at the back door. You may not be able to get structural grade in standard cartridges and would need a “sausage gun” to empty the sausage.
Even if you can find structural grade silicone in a standard cartridge it’s not cheap. AND definitely check to use by date that is only on the cardboard box.

The fact of the matter. It will cost all most as much for the silicone. razor blades , acetone ( cleaning fluid) as the cost of a 4 foot tank from the rubbish dump recycling shed ( $40 ) .

Short answer.
Its a heck of a lot harder than most Utube channels would have you believe.

Chances are the second hand tank will be fine. As long as it was built with structural grade silicone in the first place.?


I agree that properly resealing a tank is A LOT of work. Then there is always the chance that you get all done only to find you still have (or now have!) a small leak. Been there, done that. The only tanks I will bother resealing now are the antique stainless steel frame tanks, because I fancy them and they do have decent collector value.

My advice to you is clean and inspect your new tank as best you can. If all the joints look solid give it a water test in a safe location for several days. If it passes then you can go ahead and safely use it.


Thanks for your opinions Ive always highly valued them, I'll do water test when I get them..

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