2 | Red Sea | Reef Care Program
Nitrate NO3/Phosphate PO4 control
Micro-biological reduction of algae nutrients (nitrates & phosphates) occur naturally in all
anoxic areas of the aquarium (inside live rocks, porous lter media and substrates). This
bacterial activity is limited by the availability of suitable carbon sources and mineral co-factors
and under normal conditions is unable to reduce all of the algae nutrients generated on a
regular basis. Supporting the natural processes by regular dosing of a suitable carbon source
and mineral co-factors provides an easy and reliable method of incremental control of the
algae nutrient levels to safely control both the presence of nuisance algae and the population
of the symbiotic Zooxanthellae.
Coral’s Symbiotic Zooxanthellae Algae
Understanding the role played by the symbiotic Zooxanthellae algae and their relationship with
the coral is essential for successful implementation of the algae Management program.
In nature corals host Zooxanthellae inside their soft tissue. The corals derive approx 85% of
their energy from the Zooxanthellae and produce the remaining 15% in their soft tissue by
metabolizing coral nutrients (Carbohydrates, Amino and Fatty acids) that are available in the
surrounding water. This energy fuels all of the corals’ metabolic processes such as protein
production and coral skeleton growth.
The Zooxanthellae use the strong sunlight on the tropical reef as their primary energy source
and pass on up to 95% of their photosynthesis products (Carbohydrates, Amino and Fatty
acids) to their coral host and utilize the balance for their own metabolic processes. The coral
host provides the Zooxanthellae with nutrients, nitrogenous compounds, phosphates and
CO2. It is this symbiotic relationship, involving the recycling of nutrients, that is the key to the
ecological success.
Another aspect of this symbiosis relates to photo-protection from strong radiation. In nature,
the Zooxanthellae protect the corals from intense UV radiation by absorbing the light energy
and shading the delicate inner layers of the coral soft tissues.
In nature the Zooxanthellae population is controlled by the algae nutrients (nitrates and
phosphates) excreted by the coral, however in an articial reef aquarium the amount of algae