Synopsis:

Maintaining ultra-low (e.g. immeasurable) nutrient concentrations in reef aquaria and precisely-controlling the inorganic and organic substances entering the system can result in vibrant coloration of zooxanthellate corals and their allies. The method described below can accomplish this task. It should be stated from the onset that this method will only produce dramatic results if it is employed continuously, and as directed (with slight adjustments made to dosing as dictated by the appearance of the aquarium inhabitants). It is an interesting, highly-effective method of maintaining reef aquaria that is without question geared to the more “hands-on”, experienced reef aquarium enthusiast.


Stated simply, this method removes undesirable nutrients and provides beneficial nutrients. To be slightly more descriptive, it:

• Extracts phosphate, ammonia, and dissolved organic material from aquarium water by direct adsorption.
• Limits production of nitrate and minimizes the presence of latent organic material in the system.
• Provides specific organic and inorganic substances for the express purpose of enhancing health, growth, and vibrant coloration of corals and their allies.



Note:
It should be stated that we are not claiming to have pioneered the method described herein by titling this document “The Brightwell Aquatics NeoZeo Method”; we are simply outlining the method utilizing Brightwell Aquatics supplements and filtration media for the reference of interested reef enthusiasts. Additionally, no amount of tinkering with methods of filtration or nutrient supplementation will provide the desired results if the remaining water parameters and physical conditions are not within the proper ranges; it is presumed that temperature, pH, alkalinity, and the concentrations of magnesium, calcium, potassium, strontium, and important minor and trace elements in an aquarium are properly maintained, and that lighting and water flow are adjusted to address the needs of the aquarium inhabitants, in any system in which the NeoZeo (or similar) method is employed. For many aquarists, this is a somewhat complex system when first reviewed; we can just hear people saying “Ye gads!” (or the like) once they have finished reading this document. Be assured that the information provided below is meant to be a comprehensive introduction to the method, but that there are bound to be exceptions or conditions presenting themselves within specific aquaria that necessitate some degree of divergence from general dosing recommendations made; therefore, it is up to each aquarist to know their system well, for this method relies heavily on attention to detail (specifically the impact that individual components utilized have on the appearance of aquarium inhabitants, and this only comes with time and experience).


Throughout this document, the word “nutrient” will appear many times. It is used in the broadest possible context, adhering to the definition of a nutrient being a substance that provides sustenance.



Discussion:
Maintaining a healthy reef aquarium (or any aquarium, for that matter) is largely dependant upon limiting the concentrations of nutrients such as nitrate and phosphate; in doing so, the general health of the inhabitants tends to be relatively high (presumably because more attention is being paid to water quality) and the appearance of the system remains more pristine. So-called “nuisance organisms” such as filamentous algae and cyanobacteria are rarely visible in systems with immeasurable phosphate, and stony corals maintained in such systems are generally more vibrantly-colored as opposed to being predominantly brown or a shade thereof (an appearance that is the result of the high population density of zooxanthellae in the coral tissue, caused in large part by an elevated phosphate concentration in the system). Photosynthetic organisms require a usable source of phosphorus and nitrogen if they are to survive and flourish, so some small amount of these elements must be present for these organisms, and their symbionts, to survive; the key is to provide the nutrients directly to the organisms in an appropriate form and limit their “free” concentration in the reef aquarium. There’s nothing revolutionary about this concept; rather, the method in which it is accomplished (as described in this document) is somewhat new.


The NeoZeo method can be dissected into two main areas of focus: Nutrient Limitation and Nutrient Supplementation. While we will examine them individually, it is extremely important to state that this system relies on a balanced combination of the two aspects in order to provide positive results. It is extremely simple to strip the important substances out of an aquarium to the point that the aquarium inhabitants begin to suffer and perish; it is even simpler to overload an aquarium with organic and/or inorganic substances, resulting in the same fate of the inhabitants (albeit by different means).


Nutrient Limitation

As previously mentioned, controlling the concentrations of nutrients, and their precursors, in reef aquaria is extremely important; the long-term overall health of the system is highly reliant upon it. This entails extracting dissolved and particulate organic material, as well as phosphate and nitrogenous molecules such as ammonia, nitrite, and nitrate from the system efficiently and effectively. In the past, aquarists have utilized protein skimming, activated carbon, and ion-exchange resins in conjunction with the natural biological and chemical reactions taking place within sediment and porous substrates to accomplish this goal. The aspect of this method that makes it “unique” is the utilization of a family of selective zeolites for the dual purpose of extracting ammonia/ammonium and providing a substrate for the colonization of beneficial microbes. It follows that an aquarium with efficient extraction of ammonia before it is utilized in the nitrification process will have a very limited propensity for nitrate accumulation. Similarly, by extracting dissolved and particulate organic material from the water before it has a chance to be broken down via microbial processes and/or photodegradation, the constituents of that material are not released into the system; this is accomplished through protein skimming and the use of high-quality activated carbon. The rates of nitrogen and phosphorus input and the presence of adequate organic carbon largely determine whether or not some amount of measurable nitrate and/or phosphate persist in an aquarium; nitrate is removed via denitrification and/or the use of a sulfur reactor, and phosphate is addressed by utilizing some form of phosphate-adsorption media. The ultimate goal is to maintain microbial biomass production at such a rate that the concentrations of nitrate and phosphate never become measurable.


Biological Nutrient Limitation (Microbes and Organic Carbon)

The role that microbes play in a zeolite filtration method is extremely important: they convert nutrients existing in excessive concentrations into biomass, which is then (in the case of planktonic bacteria, or “bacterioplankton”) consumed by corals and other suspension-feeding organisms and utilized in biological processes, and/or removed from the aquarium by protein skimming. The process may be thought of as nutrient recycling and export, and in that regard it provides some of the same benefits that a refugium housing macroalgae provides; the main difference is that the nutrients assimilated into microbial biomass are at least partially available to corals, which is not the case when it comes to nutrients assimilated into macroalgae tissue. A percentage of the microbes form biofilms on inanimate objects (often appearing as a brownish film on the panes of the aquarium), which can be brushed off and captured by aquarium inhabitants and skimmer intakes, again exporting nutrients from the system; we will return to the topic of biofilm shortly. Before we move on, it is likely that some readers will ask the questions, “Why is this means of nutrient export any different than the natural processes taking place within any cycled aquarium? Microbes are going to colonize the NeoZeo media regardless of seeding it. What’s the big deal?” The primary difference between a “traditional” system in which biological filtration media is set into place and allowed to become passively populated with microbes and a system in which a select group of microbes is supplemented on an ongoing basis is that (again) the enthusiast maintains more control over the rate of nutrient export, and simultaneously encourages the biological processing of various substances known to negatively impact water clarity and/or the health of the aquarium inhabitants.


It is here that the discussion turns to carbon limitation and the implications this has with regards to the ability of microbes to assimilate phosphorus and nitrogen. Covering this topic requires elementary thinking and relies on the ratios of nutrient uptake in bacteria being somewhat analogous to that of marine phytoplankton.

Using the molar ratios of 106:16:1 C:N:P (carbon : nitrogen : phosphorus) in marine phytoplankton as a model for nutrient uptake in bacteria, it follows that bacteria require considerable carbon to assimilate nitrogen and (particularly) phosphorus. In a system with low- to immeasurable-concentrations of nitrate and phosphate, there is presumably sufficient organic C present to enable bacteria to utilize the N and P that is available; resultantly, bacterial biomass is regulated by the relative abundance of N and P. Conversely, in a system with relatively high concentrations of nitrate or phosphate (e.g. one that tends to be heavily-fed), their uptake by bacteria will be inhibited by inadequate organic C. The solution is to supplement the system with organic C, which enables assimilation of the existing N and P into bacterial biomass. As previously described, the bacteria, and hence the N and P, are then removed from the system via filtration and/or converted into biomass of suspension-feeding organisms capturing bacterioplankton and pieces of biofilm that become dislodged from static surfaces.