Leaks are a nuisance, but it's not usually essential to empty the tank to do a repair. The tank should be given a chance to correct its own leak. It'll frequently do this supplied the seepage isn't too quick. A leak rights itself when the suspended matter in the water clogs the fault via which the water is leaking. This procedure might take up to a week. To stop a pool of water forming on the floor, attach a strip of newspaper to the underside of the tank just below the leak, this will absorb most of the water prior to it reaches the floor. When the paper becomes perfectly dry the leak is cured. If, nevertheless, it doesn't stop within a week, the cement should be scraped out between the glass and also the frame to a depth of approximately 0.25 in., a hack saw blade broken in half offers a handy tool for this purpose. If bent back upon itself, the broken edge will have a slight curve which will act as a scoop. Remove the old cement about 1.5 in. to every side of the seepage. Next, thoroughly mix red lead with gold-size to a sticky paste. This should be forced down into the crevice with a hack saw blade, or any comparable flat tool. When the paste is set, touch it up with paint to match the existing colour.
A truly poor leak demands attention from the inside. The aquarium should be emptied and left to dry for a minimum of a week to make certain removal of all of the moisture in the cracks, then prop the tank at an angle of about 30° and run gold-size down the inside corners. Little fountain pen filler could be utilized to apply the gold-size. Don't attempt to use the tank until a minimum of a week after this treatment. A more convenient technique would be to use a proprietary sealing compound, supplied generally in a tube with a nozzle to make the application simpler. Should you prefer this technique, make certain that you use a sealer specially made for aquarium use. General kind sealers might contain toxic chemicals which are harmful to the fish.
A cracked piece of glass can't be successfully repaired, the entire pane should be carefully knocked out, old cement removed, along with a new piece of glass inserted.
A spare aquarium should usually be component of the aquarist's equipment. I know it's a fantastic temptation to use it on one pretext or another, but I advice you to keep it empty of fish to ensure that in the event of an accident it's ready for immediate use.