Leaky Tank?

[Floyds mum]

I recieved a second hand tank and it is water tight but the towel its sat on is soacking wet and i have to top it up every other day
Its a wet/dry filter, could it just be filled abit too full?

 

[fish_tank0311]

First you say its watertight, then you say the towel underneath it is soaking wet? Is it watertight or not? If it leaks seal it with silicon.