In this paludarium design, a divider is glued with sealant to separate the water portion from the dry portion of the paludarium. This divider is usually glass or plastic, and is often hidden by gluing rocks, cork, or other materials to it's face. The water portion is set up like a regular aquarium; the best way to filter it is with an internal filter or by having holes drilled for an outside canister filter. This way there are no hoses descending down the dry portion of the tank.
The dry portion should have a drain or water from watering the
plants and from condensation will not be able to escape, and it will
become muddy. If allowed to sit in stagnant water, most plants'
roots will rot and they will die. The plants should be watered
periodically on the dry side of the tank, because the aquarium water
is kept separated and condensation alone may not be enough to provide
for the plants. While this type of paludarium can be done very nicely,
it has limitations and is not ideal, in my opinion, because it fails
to truly incorporate the water/air interface, and there is no true
relation between the dry and wet areas of the tank.