Re-sealing tank question

[earhtmother]

Sellwr had tank set up 10+ years no leaks. When drained in Nov/Dec to store he discovered silicone like this - going to reseal inside and out in discoloured areas BUT can I just seal ovee top or do I have to scrape off old crap first? Since it won't be seen, not caring what it looks like as long as it doesn't leak

 

[Allanhep]

You will need to scrape out the old stuff as silicone will not stick to silicone and would be a waste of money and time trying to seal over the old stuff I bought a second hand Trigon that was the same as your aquarium problem was once the aquarium has been stored the silicone that was submerged becomes dry and brittle had a friend who made the mistake of silicone over the old stuff the new silicone came loose and his 120g sprung a massive leak he had to strip down the tank and do the silicone from scratch