i am getting a 180 gallon. should i get it drilled so i can use a wet/dry? if i do that i can make the filter just like how i do a pond filter right with the water flowing into a bow with mehcanical filtration media then it drips onto the bio media. would it be harder because with my ponds i just use gravity to let it all flow back in but for an aquarium i have to pump it back? ayone have clear diagrams i can look at. thanks-john