Having the right kind of filtration and plenty of it will help provide the best water parameter levels and consistency to support life in a marine environment. The three kinds of filtration:biological, chemical and mechanical all demonstrate that life can be supported and maintained in a closed system environment while employing efficient and effective filtration means. The trickle filter, also known as wet/dry or bio-wheel tower filter has been around for many years and has also been a popular mechanical and biological filter since its initial development.
The trickle filter consists of three main parts: drip/trickle plate, bio material and pre-filter. All three components of the trickle filter are very unique and crucial to the overall construction and benefits provided by this form of filter. This filter is also known as an aerobic filter that supports a perfect environment for the growth and population of aerobic bacteria that works at breaking down ammonia to nitrites and nitrites to nitrates.
How the filter works is water leaves the main tank and is deposited into the trickle filter through the spray bar. The water then proceeds through the pre filter where sponge, floss or micron net traps detritus and other larger pollutants and contaminants before they make their way down into the trickle filter. From the pre-filter area the water flows down across the drip plate where it then is disbursed down into the bio media where, mixed with oxygen enable the growth and population of aerobic(oxygen present) bacteria to break down the nutrients and purify the water.
Their is a diverse number of bio media that can be employed in a trickle filter as well as the ability to employ more than one drip plates. Plastic floss, ceramic noodles and other porous concoctions are all great choices. These offer a greater surface area with which aerobic bacteria can adhere to and grow in efforts to combat the dissolved organics and other contaminants produced by the bioload from the main tank.
The more oxygen you are able to provide the filter the better to saturate the oxygen level pertinent to the success of the aerobic bacteria. Also their are a couple glitches with this type of filter, the first being that the pre-filter will need to be cleaned regularly to increase oxygen and not to impede the water flow through the trickle unit. Depending on the bioload, you may have to clean the pre-filter more than usual for the trickle filter to perform efficiently and effectively. The religious devotion to cleaning the pre-filter has alot to do with the second glitch regarding this filter. For the most part, trickle filters are great at riding a tank of ammonia by breaking it down into nitrites and then into its least toxic form nitrates, but that is where the filters effectiveness ends. Normally associated with the term “nitrate trap” these filter type does an excellent job until it gets to the nitrate breakdown.
With the employment of a cannister or trickle filter you may want to remove the bio media and replace it with live rock as a newly upgraded sump version. This will better allow bacteria as well as other diverse living organisms that may reside on and in the live rock to flourish and offer you all the benefits provided by the plethora of infauna. I think that this type of revamping of the trickle or cannister filtration will offer much more to maintaining a marine aquarium. Nitrifying and denitrifying bacteria will be present as well as the living organisms that can be as diverse as one piece of rock to another.
When choosing to remove the bio media if you have been using it for awhile, it is best to remove a little at a time to reduce the chances of water parameter issues unfolding as bacteria levels drop. If you are going the live rock route right from the get go, then acclimation time is a mute point and the employment of the live rock can all be added right from the start.
As for the decision to add a trickle filter, sand filter or even a cannister type filter, these are better suited for a saltwater fish only tank due to the amount of fish and surface area. When setting up a reef biotope, the influx of live sand and rock combined with the protein skimmer, water changes and strict feeding regimen, you should have enough bacteria and other living organisms to aid in the reduction of ammonia, nitrites and nitrates as well as phosphates, silicates and other dissolved organic matter and particulates. You also have to factor in the fact that many filter feeding invertebrates such as fan worms, sponges and tridacna clams will feed upon these nutrients as well as many corals.
The trickle filter has been around for a long time and is very popular with aquarists so it must have some benefits to employing this type of filter to a marine aquarium. It just seems like a redundant piece of equipment with regards to a marine reef biotope. You could spend that money on lighting upgrades, supplies or new inhabitants for your aquarium. If nothing else, I would remove the bio media and replace it with live sand or rock to really enhance the ability of your trickle filter in helping to ensure that your filter is running effectively and providing more benefits.