The Jaubert System Revisited
by Mike Paletta - SeaScope Volume 14, Winter 1997

It has now been four years since what has come to be known as the Jaubert system of reefkeeping was introduced. I have used modified versions of this system in two of my own tanks as well as in six other tanks, all of which have been set up for at least one year. Two others have been set up for almost three years. After working with this system in several different forms, I recognize both its strengths and inadequacies.

When this concept was first explained it seemed simple enough: use a plate to produce a space for water (a plenum) under a bed of live sand to allow for anoxic conditions to develop. When the oxygen levels in the plenum fall low enough, processes will occur that convert nitrate into nitrogen gas. In addition to lowering nitrate levels, there is also a gradual dissolution of the carbonate live sand bed, which produces a constant introduction of calcium, strontium, and trace elements into the tank.

I set up tanks according to this simple system, but it seems I did not read all the fine print. The patent by Dr. Jaubert as well as videotapes and lectures by him and his staff reveal that this system is not quite as simple as it appears to be. As a result it has been my experience that success using this system depends on a number of variables. Some of these variables and the effects of small design alterations follow.

As would be expected, the quality of the live sand bed is critical to the success of this system. The type of sand chosen is of course important. Its inhabitants have a major effect on the processes that occur in and under the bed. I refer now to the amphipods, copepods, burrowing molluscs, and particularly the worms. Jaubert describes a mini-ecosystem within the live sand bed that is critical for the success of this system. Unfortunately it has been my experience that very few of us are able to obtain live sand with the quality of inhabitants that Jaubert describes. In particular, worms and burrowing molluscs are almost always missing from the live sand that is available. This seems to be a distinct disadvantage, because these animals act in a manner similar to their terrestrial counterparts: they aerate the sand and remove any small bits of organic matter that lodge there. The lack of worms and molluscs is probably a result of live sand collection from areas devoid of these creatures, or from crushing during shipping. In either case, lack of these critical components of the live sand bed starts us off at a disadvantage. Without them the sand is not adequately aerated, resulting in dead spots. Organic matter accumulates in the substrate and results in an increased likelihood of algal blooms.

Another crucial component of the system is sand-sifting organisms. Jaubert uses brittlestars, sea cucumbers, hermit crabs, and sand-stirring fish to further aerate the sand. In many instances the quality and quantity of these animals in our tanks is also low. Many of us also start off with only a small amount of actual live sand, with the rest of the substrate being dead aragonite sand or crushed coral sand. We hope that we can inoculate this dead sand with animals from the live sand. This may occur over time, but most of us are not patient enough. As a result we stock the tank and feed the inhabitants long before this sand is fully mature. Once again this results in the accummulation of waste and decaying material that acts as a nutrient sink.

One other aspect of Professor Jaubert's system that has gone almost completely unnoticed is that, for the most part, the substrate does not have much live rock or corals resting on it. Jaubert attaches most of his corals and live rock to the side walls of the tank. Thus the substrate is not compacted and does not have rock-algae interfaces that act as detritus traps. In most of jaubert's systems less than 30% of the substrate has anything resting on it. This helps to limit the amount of waste and detritus that accumulates. Unfortunately, this large amount of open surface is the exception rather than the rule in many of our tanks.

There has been debate about whether these tanks are actually closed systems. They are all at least partly open and many get as much as a 10% water change with ocean water each week. This further reduces any buildup of nutrients.

Based on the design details already mentioned, I no longer recommend this system for the typical hobbyist. My own two tanks experienced algal blooms within two years, forcing me to remove the Jaubert plates and most of the substrate. I did not make this decision lightly, because they were a 90 gallon tank and a 400 gallon tank. The 400 gallon tank contained 24 square feet of substrate three inches deep. Once I removed the plates and the substrate it took three months for the algae to die.

In the remaining six tanks that I helped set up using this system only two are free of algae and none have nitrate levels lower than 5 parts per million (ppm). The two successful tanks both contain high-quality live sand and have less than 40% of the substrate covered by live rock.

I believe that several other factors influence how successful an aquarium set up on Professor jaubert's system will be. Use of a protein skimmer may affect the dynamics of this system by removing organic material that might otherwise act as a nutrient source for the anaerobic bacteria. Ozone and carbon levels may also have some impact. My tanks are smaller and contain a much higher ratio of animals to water than jaubert's tanks. This probably has a negative impact on the system. I also make water changes less frequently.

Despite all of this I will probably continue to experiment with the jaubert system, but I will make one major change. Thejaubert plate and substrate will be in an external chamber separate from my tank. If problems do arise the system can be simply taken off line without the effort now required to remove the plate and substrate.