Personally, I do not have any sponges or filter cartridges, etc. I most definately do not have a wet/dry filter.
I use live rock, protein skimming and two 330gph hob filters with filled with live sand (in a nylon stocking).
The only mechanical filtration I use is the sponge over the intake for the protein skimmer, and I have no choice on that.
Mechanical filtration quickly becomes biological filtration if not cleaned at least daily.
Utilizing the high water flow (25x), the protein skimmer, and an abundance of live rock, my water parameters are always immaculate (listed below). You can see that the Berlin Reef system works quite well.
Temp: 80-84 (never fluctuates more than 2 in a day)
PH: 8.0
Specific Gravity: 1.024
Ammonia: 0.0
Nitrite: 0.0
Nitrate: 0.0
Phosphate: 0.0
Calcium: 640 (Its high I know, I've stopped the kalkwasser for now)
ps- bioballs are the
(my opinion)