phanmc said:For a saltwater tank, an overflow with a wet/dry system is very desirable. Nothing beats the biological filtration of a wet/dry system.
Live rock and/or a deep sand bed (DSB) are WAY better biological filters - they complete the proccess and convert ammonia into nitrite,nitrite into nitrate and then nitrate into nitrogen gas, unlike wet/drys wich only convert ammonia into nirtite and nitrite into nitrate (leaving you with nitrate problems down the line). It is true that there excelent bio filters if you only want nitryfing bacteria, but the well researched marine aquarist will usually want/need the denitrifying bacteria as well. Not to mention, if your power goes out for more than 20-30 minutes, you can count on most of the bacteria in a wet/dry to be dead, sending your tank into a mini cycle, while with live rock and DSB's, your bacteria stays submerged and almost all the bacteria should survive a 2-3 hour power failure, probably even longer then that.