Wet dry filters were at one time, "THE" filter to have.
For the last 12 yrs or more, other systems have come to the forefront and have for the most part, relegated the wet dry to fish only systems.
The wet dry is a highly efficient system, quickly changing the ammonia to nitrite and the nitrite to nitrate.
However, because it lacks anerobic areas, it is incapable of converting the nitrates which will accumulate in the system and will require many water changes or a nitrate removal system to make it suitable for a reef tank.