Saltcorner
By Bob Goemans
By Bob Goemans
Dear Bob,
I have several reef systems that have a plenum system installed with a trickle filter. All of the systems have sufficient live rock included in the aquarium itself and a good protein skimmer. They are stocked with numerous corals and a moderate number of fish. Would you agree that the systems would function best without the bio-balls in the trickle filter? Wouldn't the trickle filters function as a sump without the bio-balls? I have one 400 gallon system that has bio-balls added in a header box and in a sump where they are completely submerged by water, as well as bio-balls in a trickle filter. Would you recommend removing them as well? I have read that trickle filters are producers of nitrate. Do you agree?
Thanks for your response.
Tom Gray
Hi Tom,
The sole purpose of bio-balls is to provide adhesion sites for nitrification bacteria. The bacteria's sole purpose is to oxidize the ammonia-laden compounds flowing past them and reduce it to nitrate, which is the processes final product. The location of the bio-balls in an area where water 'trickles' over them helps to replenish the oxygen used by the bacteria in the reduction process. Should the media be submerged, the oxygen used by the bacteria is not replaced and distracts from the overall dissolved oxygen in the bulk water.
So yes, trickle filters generate nitrate and it's the reason why I recommend this type equipment not be used in conjunction with/on plenum systems. It's actually preferable to allow the majority of nitrate production to occur in the upper plenum sandbed and diffuse downward to be used by the very efficient microbes living in the lower anoxic portions of the bed. In plenum systems, having any equipment that distributes nitrate laden water into the system's bulk water is counterproductive and not in the best interest of overall water quality.
As long as you have a quality protein skimmer that helps keep system water well oxygenated, the trickle filter is not needed. Yet, if you want to keep the unit in action, its media should be removed, however, not all at one time. Removing equal portions of the bio-balls over a few months is the way to proceed. In place of the bio-balls in the trickle section some hobbyists use small pieces of live rock and/or small containers/sacks of phosphate removing media/activated carbon. That's fine, as is the installation of acrylic deflector panels arranged so as to lengthen the flow of the water passing through the trickle section, which helps add some oxygen. As for the unit's sump, it's the ideal place to makeup for evaporation, add various additives, and/or house various helpful pieces of equipment.
In other than plenum systems or where high nitrate levels are not a concern, the use of trickle filters and/or fluidbed filters is quite effective.
Hope this helps,
Bob
