Why is water quality important at the Georgia Sea Turtle Center?

One the most important aspects of aquatic animal husbandry is maintaining good water quality. Having an environment that is suitable for the animal to live in is paramount and knowing when to alter that environment takes initiative on the part of the caregiver to know each animals requirements. This can mean maintaining the filters, having an appropriate animal load and understanding the chemistry and biology of the system.

At the GSTC we test our water in our systems weekly. Some routine tests are pH, ammonia, nitrite, nitrate, salinity and ozone. More specialized tests may include hardness, alkalinity, coli forms and chlorine.

How are the results interpreted?

pH
pH refers to the amount of hydrogen ions in a solution and can range from 1 to 14. A low pH means that there is a high level of hydrogen ions and that the solution is acidic. A high pH means that there is a low level of hydrogen ions and that the solution is basic. pH is determined by testing with a probe that is placed in the tank.  Turtles in the wild generally live in water that maintains a specific pH or at least a very narrow range. It is important to match those levels in our hospital tanks to achieve maximum health.

So, what is optimal pH?  Saltwater systems should maintain a pH between 8.0-8.30 which mimics natural sea water.

Ammonia
NH3+ is the measure of nitrogen ions in the form of ammonia. This is tested using a spectrophotometer that was graciously donated from the HACH Company. Animals produce waste in the form of ammonia and it is toxic in high levels. Ideally a healthy system will not have any measurable ammonia, but additions of medications, overfeeding, or a broken filtration system can cause ammonia levels to increase.

Nitrite
NO2- is the measure of nitrogen ions in the form of nitrite. The test for nitrite is done on a spectrophotometer.

Nitrate
NO3- is the end result of the nitrogen cycle and is not toxic to animals unless it reaches extremely high levels. Nitrate is measured on a spectrophotometer.

Salinity
The salinity of natural seawater is 32ppt or a density of 1.025. An Estuary’s water salinity will vary between 12 and 25ppt. Salinity is measured using an instrument called a refractometer. By placing a small amount of water on the refracting lens, the salinity can be measure by looking through the optics and seeing where the light refracts against a scale.

Filtration

The life support systems

The life support systems (LSS) at the Georgia Sea Turtle Center are top of the line for sea turtle rehabilitation. There are six systems, each individually having three constant loops of filtration running.  The three loops are a bead filter with a chiller, low space bioreactor (LSB), and protein skimmer with ozone injection.

The salt water in our systems is a synthetic sea salt mixed on-site and stored in a 2200 gallon salt water storage basin at 30ppt salinity.

Bead filter/Chiller - this is a form of mechanical filtration which is a forceful stream of tank water running through a vessel of silicon beads. The beads filter out larger particles in the water. Then the water runs through a chiller which can heat or cool the water depending on the temperature setting.

Protein skimmer/ozone - removes dissolved organic compounds by creating foam. Bubbles that are created have a lot of surface tension.  Organics stick to the surface tension, which add in the removal of proteins and other organics out of the water. At the same time ozone is being produced and being injected into the water through the protein skimmer.

LSB - is a container of tiny plastic beads that have a lot of surface area. On the beads live millions of nitrifying bacteria which filter the water.