Choosing Your Biological Filter Material

How To Choose the Right Bio-Material For a Wet/Dry Trickle or Other Type of Saltwater Aquarium Biological Filter

The efficiency (square feet (sq.ft.) of surface area per cubic foot (cu.ft.) of each material is easy to determine from the table below. The volume of material used in a particular system will be determined by the filter design.
 

Unfortunately with increased efficiency comes greater maintenance.  The smaller the channels through the material, the more solid material (food, detritus, etc.) will be stopped, blocking water flow and reducing efficiency.  In general, the higher the efficiency of the material, the more easily the material will clog, with sand and carbon being the worst offenders. Any bio-material can be cleaned. Passing the water through a good mechanical filter before it reaches the biological filter media is highly recommended, as this will greatly reduce maintenance on any material, but inevitably, the material will need to be cleaned. Cleaning the bio-material will dislodge a certain amount of the resident bacteria, along with the clogging foreign material. This will temporarily (until bacteria can repopulate) reduce the bacteria population and the capacity of the biological filter to convert ammonia to nitrates.  Since we don't want to reduce the bacteria level to a point where ammonia spikes occur and unprocessed nitrites become evident, cleaning the bio-material should be performed in steps.  Periodically cleaning only a portion of the material before reinstalling it in the filter will help avoid a catastrophic reduction in biological filtration.  (See How To Clean Dirty Bio-Balls Instructions & Tips)

When designing a filtration system and choosing a filter material, consideration should given to how easily a portion of the bio material can be removed for cleaning, while leaving the balance of the material intact.  Loose materials (various forms of Balls, Beads, Bales, Barrels, sand, gravel and carbon) can be installed in easy to remove porous "packets".  Each "packet" can be removed, cleaned and reinstalled in the filter without disturbing the others.  The Nylon Pot Scrubbers are among the easiest to maintain.  Since they come in sheets, they can be stacked, either vertically or horizontally.  The individual sheets can be removed from the front (input side) of the filter, cleaned and then replaced at the end (output side) of the filter without disturbing the remaining sheets.

Another factor to consider is the velocity at which the water passes through the filter medium.  Many people have found that to maximize a biological filter, the tank water should be turned over 6 to 10 times per hour.  This presents the ammonia/nitrite molecules to the bacteria at the best rate for conversion.  Sand, though a good bio medium, would be difficult to contain at this velocity.  Most of the bio balls, barrels, loops, hoops, etc. are designed to allow for maximum water flow, making them better for a high velocity filtration system.

With some forethought and a little ingenuity you should easily be able to put together a filtration system that is easy to maintain, as well as fulfills all of your biological filtration requirements.

~ Debbie & Stan Hauter