I have a Fluval 304, i have replaced the o ring, and other parts. However it still leaks. I have invested already past what my wife allowed on this canister ( i should of just scrapped it and bought a new one). Tonight i siliconed the lid to the canister, and then to be safe i hot glued it... well water still drips from different locations. I have used 2 tubes of aquarium silicone and 4 large sticks of glue (non toxic).. For the sake of arguement, and to prove my wife wrong.... how can i get it to stop leaking?