Many cichlids are primarily bottom dwellers, venturing up into the water column on rare occasions. This increases the potential for stirring up detritus and other elements that collect on the substrate. Aquarists who maintain tanks with driftwood and/or live plants know all too well how quickly solid matter can accumulate. Regular substrate vacuuming when performing water changes will reduce the amount of detritus available to get stirred up. Since I primarily keep dwarf cichlids, I generally don’t have a problem with waste and other organic material getting kicked up into the water column, where the filter intakes are most likely to draw it in. However, I still prefilter all of my filters.
What is prefiltering? Basically, it’s a type of mechanical filtration that precedes the regular filter media. Most filters utilize an intake tube strainer on the end of the intake that primarily blocks the larger pieces of debris from reaching the filter media. By prefiltering, you can stop all but the finest particulate matter, regardless of the type of filter you employ (HOB, canister, internal, sump). Consequently, this can reduce the frequency of cleaning your primary filter, prevent items from clogging up the primary filter, and add more surface area for biological filtration.
The simplest and most cost efficient method of prefiltering is to use a proper fitting sponge over the intake. The only real drawback is the potential reduction in water flow to the primary filter, but I’ve found this is only a problem with higher flow filters when using prefilter sponges that are especially dense. Above are some photos of various sponges I use. You can pick these up at your local aquarium store or even order online.