Change Underground Filter To A External Filter?

[Pkn]

my underground filter has a tube comming from under the gravel, then it is connetted by another tube that reaches a pump just above the water then the water goes from the pump to throught the filter media the box is (outside of the water) then back into the fish tank. i was watering if i took out the bottom tube that connects to the ground. the tube will be sucking water from the middle of the tank instead of water from under the gravel?. will it work as a nomal filter? or there is more to it? thankyou in advence for your help

 

[rabbut]

It would work as a trickle filter, just with less bio-media capasity. I'd personally keep it as it is, or swap to a completely different filter