Brackish water environments, the least understood and replicated biotopes, offer a tremendous opportunity for pond builders to expand their business. Unfortunately, these dynamic zones have a reputation for being dreary and mucky. In nature, brackish water tidepools and backwater areas are turbid — but so are most of the rivers and streams from which our prized fish originate!
Brackish water is typically found in estuaries where freshwater and seawater merge. The salt content of brackish water falls between pure freshwater’s specific gravity (1.000) and seawater’s specific gravity (normally ≥ 1.025). These brackish-water areas are dynamic transition zones where the salt content is constantly changing due to rainfall, tidal shifts, droughts and other acts of nature. Brackish waters are home to a hugely diverse array of flora and fauna.
Location, location, location
Navarre Beach is considered Florida’s best kept secret. With its sugar-white sand, emerald-colored water and family-friendly atmosphere, it offers everything for a reserved and educational vacation. Families love Navarre Beach and the learning experiences offered by the Sea Turtle Conservation Center.
Navarre Beach resides on Santa Rosa Island in Florida’s panhandle. To the south of the beach is the Gulf of Mexico, where the waters are teeming with sea turtles. It is a sea turtle nesting haven given its quiet atmosphere and vast, pristine beaches. The identification and protection of the sea turtle nests and, sadly, the rescue of injured turtles were the motivations for creating the Navarre Beach Sea Turtle Conservation Center.
On the north side of Navarre Beach is Santa Rosa Sound, which in many areas is brackish. The sound is a breeding ground for both freshwater and saltwater species. Pods of adorable dolphins frequenting Santa Rosa Sound attest to the area’s bountiful sea life.
Indoor brackish water ponds
The clear waters of Navarre Beach and Santa Rosa Sound are replete with biodiversity. A brackish water indoor pond fits in with education, one of the center’s three mission pillars along with sea turtle conservation and research.
The Navarre Beach Sea Turtle Conservation Center’s 3,500-gallon indoor brackish water pond is a culmination of vision, creativity, determination and necessity. Conservation Center board member Carmen Reynolds secured the grant to build a new conservation education structure. Grant money and generous donations from the community funded the project.
Cathy Holmes, director of conservation, education and research, spearheaded the project and expertly managed to “juggle glass balls” without a fumble. Construction was a monumental endeavor. It was essential that the pond and an adjacent injured sea turtle evaluation area remained transparent to the visitors, ongoing research and education classes, never detracting from the center’s primary mission: sea turtle rescue. Holmes, her dedicated staff and a group of professional contractors made it happen with aplomb.
Construction planning
The Sea Turtle Conservation Center is located on Navarre Beach with an elevation of about 2 feet above sea level. This low elevation was a major engineering consideration during the design phase of the center’s new 1,152-square-foot structure for housing the pond. Supporting the structure’s roof are huge wooden piles that were piledriven deep into the sand.
A reinforced concrete floor was then poured. The walls, called blowout walls, are actually designed to break away from the structure during a catastrophic storm, essentially leaving a roof, concrete floor and all the support structure in place. (Hopefully, that will never occur.) A concrete pond was the only reasonable solution, since a wooden-framed liner pond would not withstand the forces of nature and the nearly 60,000 annual visitors pushing and leaning in to view the pond’s inhabitants.
Gulf Breeze Pools and Spas was contracted to build the brackish water pond. Building an indoor, above-ground pond on a concrete slab was a first for them, but looking at the finished project, one would never know. During the design stage, one absolute requirement was the necessity of keeping the facility Americans with Disabilities Act (ADA) compliant. Maintaining sufficient space between the pond and the walls and avoiding stairs and obstacles would be essential.
Permitting from Santa Rosa County for the project proved to be the first hurdle. Did this job require a residential or commercial permit? A swimming pool company, installing what appeared to be an indoor swimming pool in a nonprofit public facility, fell into the hazy betwixt. Thankfully, the county quickly resolved the issue by permitting the pond as residential so the project could move forward.
Plumbing it in
Tyler Kinports, Gulf Breeze Pools project manager, said this job was radically different from building an in-ground swimming pool. One challenge was the plumbing. Normally, the plumbing is easy when doing an in-ground pool. In this case, running plumbing from the pond across a concrete floor and through a wall into the outdoor filtration facility required engineering creativity to maintain the required visitor accessibility while also meeting the filtration needs of the venue.
The concrete floor was first scored to produce an indelible outline for the framing crew. Holes were Ramset into the floor, and then forms were constructed using plywood. The installation of the steeling (rebar) grid came next. It took less than three days to carefully do the framing and steeling.
The process was slow due to working in a confined area, keeping away from visitors and achieving the measurement exactness required for ADA compliance. All the plumbing was routed within the forms. The pipe fittings were checked and rechecked prior to filling the wall forms with concrete.
The plumbing had to be without leaks, which is unlike a normal pond or swimming pool, where a very slight plumbing leak can sometimes be ignored. This step was essential, since any leaks within the pond’s walls would require draining the pond followed by tearing out a section of the wall with the leaking pipe. Essentially, it would be major job and significant disruption to the facility.
All the connections were carefully prepared and hydro-sealed. Then Basecrete was applied as further waterproofing. More than 120 feet of 2-inch PVC, plus 80 feet of 1-½ inch PVC piping were used for the indoor plumbing. Concrete was then poured into the wooden forms. The concrete was kept moist for the first two weeks and allowed to cure for 30 days before proceeding to the overall leak test.
Leak Protection
The pond and filtration system were filled and tested for leaks. Slight adjustments to piping leading from the pond to the filtration facility were required during this two-day test. The pond was emptied so that everything could be completely inspected before it was refilled again. This second fill test lasted for more than month. The entire pond and filtration system passed the second test with flying colors.
Gunite was the first coating applied. The pond’s ¼ to ½-inch-thick gunite layer was later covered with Basecrete waterproof bondcoat system. The next step was plastering. An indoor location made spraying the plaster a little more difficult. When the plastering crew arrived, it was apparent that they were thinking, “What the heck, we are spraying this stuff indoors? Really?”
The mixing team prepared the plaster outside and ran the pressure spray hose in a serpentine manner into the building. These guys were real professionals. With visitors in the area, they paid close attention to keep the dust down while mixing the plaster. It was quite a feat. The crew first sprayed the plaster into the pond and then hand troweled the mixture on the sides. Plaster was carefully placed in and around all the pipe fittings before they meticulosity cleaned overspray with a damp sponge. It was truly a work of art.
Final touches
The filtration system is located outdoors in a lanai-like setting with a privacy fence. Much forethought went into its layout for maintenance accessibility. An RK2 Systems model RK 25 PE protein fractionator (also called a protein skimmer) removes organic waste from the water by replicating the principle of foam fractionation, which is a natural foam produced by the ocean’s wave action. The protein skimmer is powered by a programmable, 20-to-80-GPM, Pentair 1 ½-HP variable-speed pump. The processed water gravity feeds back into the pond at a rate of 25 GPM after passing through the fractionator.
Aquarist Jeff Smith added sea salt to the pond about a month after the construction was complete. The salt was incrementally added and monitored with a salt refractometer to avoid overdosing. The target specific gravity was 1.018, which is at the higher end of the brackish-water scale but necessary for keeping brackish water stingrays, which the center hopes to study. The pond will not be a touch tank; rather, it will be a brackish-water stingray and horseshoe crab research project as well as a delightful venue for visitors.
The fishless pond water was cycled over eight weeks in preparation for the stingrays. The filtration system performed flawlessly during the cycle period.
A 10-foot-tall red mangrove (Rhizophora mangle) tree was added to the venue to provide the stingrays with natural shelter. Red mangroves are the first line of defense against the powerful ocean’s surge and serve as a breeding ground and safe haven for an abundance of sea life. Including a red mangrove affords an excellent educational opportunity for the visitors to learn about the fascinating saltwater processing of these magnificent trees. The tree drinks the brackish or saltwater and deposits unwanted salt on its leaves. Later, rainwater washes the salt off the leaves.
Natural lighting for the mangrove is provided by four overhead skylights. The mangrove was grown indoors by the author from a propagule (seed) and donated to the center. The tree is more than 10 years old. This tree has been featured in multiple pond and aquarium international magazines.
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