This article is from the ReefKeepers FAQ, by several authors (see the Credits section).
Also known as Wet/Dry Filters. An improvement over UGF and RUGF
filters. Nitrates can be kept low (say, around 5 ppm) with
adequate water changes. It does not seem to be possible to keep
nitrates very low (less than 1 ppm) if a trickle filter is the
sole biological filtration. Those that report less than 1 ppm
normally have adequate live rock, and find that their Nitrates
remain low even (and often get lower) when they remove all the
bio-material from their trickle filters (turning them into plain
sumps, useful for holding carbon and as a water reservoir).
 
Continue to: