Reefkeeping 101 -
Various Nutrient Control Methods
You’ve decided to create a reef environment in your aquarium, and someone just told you to abandon your canister or wet/dry filter. You might ask “what else is there?” or “which method should I use?” The purpose of this article is to describe some commonly accepted nutrient control methods and the principle of each to help an aquarist decide which method suits their desired ecosystem and proposed maintenance regime. Please keep in mind that each method is used successfully and each has its adherents and opponents. There are other benefits to each system which have been omitted to concentrate on nutrient control. Once a method is chosen, further research is recommended. Any one of these methods improperly designed or employed, will not yield the results you may desire.
The Berlin method of nutrient control is characterized by using large amounts of live rock as a site for aerobic bacteria to convert Ammonia to Nitrite than Nitrate (nitrification) and other strains of bacteria to convert Nitrate to Nitrogen gas and Oxygen (destructive de-nitrification) in anoxic (low oxygen) and anaerobic (no oxygen) areas. One of the benefits of nitrification and de-nitrification in close proximity within the structure of the rock is that the aerobic bacteria provide the transport mechanism of nutrient to the anoxic and anaerobic zones. Other common characteristics of this method are the use of surface skimming overflow, protein skimming, Kalkwasser addition (for Calcium and alkalinity support as well as Phosphate precipitation), and supplementation of trace elements. Mechanical filtration, if used, should be cleaned regularly to limit nitrification at the mechanical media.
The Deep Sand Bed or DSB method is characterized by a six inch layer of live sugar-sized or oolitic sand (commonly aragonite based) directly on the aquarium bottom. Proponents of this grain size maintain that it provides proper flow characteristics for nutrient reduction and buffering capacity and limits detritus intrusion in the sand bed. Control of nutrient is similar in nature to the Berlin method but accomplished in the sand bed. Due to the large amounts of surface area for bacterial colonization, it has been proposed that the DSB method is efficient enough for nutrient control to use without protein skimming.
The Jaubert Monaco or Natural Nitrate Reduction method is characterized by a four inch layer of live 2.0 to 5.0 mm grain-sized aragonite gravel over an isolated void or plenum on the aquarium bottom. Control of nutrients is based upon the same principle as Berlin and DSB. The purpose of the plenum is to promote diffusion of nutrients from the surface of the substrate to the plenum based on the difference in dissolved oxygen levels at each location. The diffusion throughout the substrate increases the depth of the anoxic zone where efficient destructive de-nitrification takes place and limits the formation of Hydrogen Sulfide gas. The depth of substrate and the grain size are considered critical to success with this method. Good water circulation is required to prevent the low oxygen levels that this method can exhibit while the aquarium is not illuminated. Typically, the use of live rock is limited to increase the available area on the surface of the substrate.
The Ecosystem Aquarium® method is characterized by the aquarium water flowing through a chamber with a layer of Miracle Mud® on the bottom, and Caulerpa sp. macro-algae is anchored in the mud. This chamber is illuminated 24 hours a day. The mud provides supplementation of trace elements as well providing a site for de-nitrification. The macro-algae oxygenates the water, stabilizes pH and can be harvested for nutrient export. Portions of the mud are replaced periodically to replenish trace elements. The mud is perhaps unfortunately named as the “miracle” aspect is often derided by proponents of other methods. Protein skimming is not considered necessary.
The Algal Turf Filtration (ATF) method is characterized by the aquarium water flowing through a shallow chamber with various species of turf algae growing on grids. The water level over the algae is very shallow, and the flow is often achieved by dump buckets. The surging of water is reported to evenly illuminate the algae and provide better gas exchange. The algae are typically illuminated while the aquarium is dark (Reverse Daylight Photosynthesis or RDP) and oxygenates the water/stabilizes the pH at night. The algae are harvested regularly for nutrient export. Turf algae are reported to grow and assimilate nutrient at a faster rate than macro-algae due to the entire structure of turf algae being photosynthetic. Protein skimming and activated carbon may be necessary to remove algae products that may stain the water.
The Vodka method is characterized by the controlled dosage of a carbon source (vodka or other) to stimulate the growth of bacteria to assimilate Nitrogen and Phosphate. The nutrient and bacteria are exported via protein skimming. Skimmer production can be extremely high and any mechanical media will clog more rapidly due to bio-film production.
Other methods for controlling nutrient include Phosphate removal with media such as Granular Ferric Oxide and protein skimming, de-nitrification with Sulfur reactors or bio de-nitrators, additives for Nitrate export using a protein skimmer and ion exchange resins for nutrient removal. A zealous adherent to any of the described methods might consider any of these a stop gap measure, but each has its positive uses as well as draw backs.
“The Reef Aquarium - Vol 3 ” by J. Charles Delbeek and Julian Sprung
“Dynamic Aquaria” by Walter H. Adey and Karen Loveland
“Live Sand Secrets” by Bob Goemans
"Vodka Dosing...Distilled! " by Nathaniel A. Walton and Matt Bjornson
"How Sand Beds Really Work" by Dr Ron Shimek
If you have any questions
or comments about this article, please visit this thread in the New to the Hobby forum on Reef Central.