Considering the role your liner plays early in the design phase allows you to create ponds that are both functional and optimized for your fish’s needs and operational goals. This chapter guides you through key design principles, highlighting how the selection and proper integration of a high-quality geomembrane liner, like our AquaArmor series, can contribute to a healthier, more efficient, and ultimately more profitable fish hatchery.
Pond Shape and Size
The shape and size of your fish hatchery ponds are fundamental design decisions that impact everything from water circulation and waste management to stocking densities and overall efficiency. When planning these crucial dimensions, it’s essential to consider how your choice of geomembrane liner will interact with and accommodate your design.
Shape
Rectangular ponds promote predictable and uniform water flow, especially when combined with directional flow systems like raceways. The straight channels direct the water’s movement, making it easier to manage oxygen distribution to specific areas and carry waste consistently toward an outlet. This is particularly beneficial in higher-density systems.
However, when the flow is not correctly designed, the corners of rectangular ponds can experience less water movement and develop stagnant areas, lower oxygen levels, and waste accumulation. Careful placement of inlets and outlets can mitigate this issue.
Try This: Rectangular pond liners are the simplest to install, but an optimal layout minimizes waste, too. Leverage our team’s decades of experience to help plan the most efficient layout.
Circular or oval ponds encourage effective central circulation, which keeps waste suspended in the center (where an outlet is often located) and promotes better overall mixing of oxygenated water. However, while rounded ponds are good for overall mixing, maintaining a consistent, directional flow throughout the entire pond (as needed in some raceway-style setups) can be more difficult to achieve.
Try This: Opt for circular or oval ponds when maximizing water mixing and minimizing waste accumulation in corners is a priority, but ensure your circulation system is designed to meet oxygen demand.
Irregularly shaped ponds might be used based on site topography or aesthetic considerations. Still, they often present the most complex liner installation challenges and can require precise measurements and more intricate seaming.
Try This: If irregular pond shapes are necessary, meticulous site surveying and detailed liner layout planning are essential. For these more complex projects, consider consulting with our experienced liner installers.
Size
The size of your ponds directly correlates with your production capacity and stocking densities. Larger ponds require larger liner installations, impacting project costs, installation time, and the extent of necessary seaming.
Proper seam welding and quality control become even more critical with larger liner areas. To reduce the number of field seams and simplify installation, consider the advantages of a custom-fabricated liner. These liners are shipped in large panels and cut to fit your pond’s shape, minimizing waste and often eliminating field seams altogether.
Try This: When determining pond size, carefully balance your production goals with the practicalities of liner installation and long-term maintenance. Explore the benefits of custom-fabricated liners from BTL Liners for large-scale projects to minimize field seams.
Pond Depth and Slope
Design elements like pond depth and slope directly influence water temperature stratification, oxygen levels, ease of maintenance, and the structural integrity of both the pond and its liner.
Depth
The optimal depth of your ponds depends largely on the fish species you’re raising, the climate, and your management practices. While uniform depth is often preferred in commercial hatcheries for ease of management, it’s helpful to understand the general principles.
Shallow ponds tend to warm up, which can benefit some species or in colder climates. However, they are also more susceptible to rapid temperature fluctuations and may experience lower dissolved oxygen levels.
Try This: For shallow ponds, ensure your liner is UV-resistant to withstand increased sun exposure. Aeration systems are crucial to maintain adequate oxygen levels.
Deep ponds maintain more stable temperatures, an advantage in warmer climates or for species that prefer cooler water. They can also hold more water with a smaller footprint, which provides a buffer against water quality changes.
Try This: When designing deeper ponds, consider that liner inspection and maintenance can be more challenging. Include elements that allow safe access for personnel and equipment, such as access ramps or strategically placed platforms.
Slope
The slopes of your pond banks affect structural stability and the complexity of maintenance activities. While some above-ground installations like large raceways or long, channel-like ponds might incorporate a slight slope to aid in waste removal, they’re relatively uncommon. In contrast, in-ground ponds often incorporate slopes to promote efficient drainage and waste removal.
Steep slopes minimize land use and can increase water volume. However, they are more prone to erosion and can make liner installation and maintenance more challenging. Consistent slopes are generally preferred in commercial hatcheries.
Try This: Avoid very steep slopes whenever possible. Use textured liners or other stabilization techniques to prevent liner slippage if necessary.
Gentle slopes are easier to maintain than steep slopes and reduce erosion risk. They also simplify liner installation and allow easier access for maintenance equipment.
Try This: Design for gentle slopes whenever land availability allows. This will contribute to the long-term stability of your pond and liner system.
Special Liner Considerations for Slopes
- Since gravitational pull on a liner increases with the slope, choose a liner strong enough to withstand the pull and potential stress from settling or movement of the pond banks.
- On steeper slopes, textured liners can increase friction with the underlying soil and prevent slippage.
Try This: Research the optimal depth ranges for your chosen fish species and prioritize gentle slopes for ease of maintenance and long-term stability. Consult with liner specialists to ensure your chosen liner suits your slope design.
Inlet and Outlet Structures
Water needs to circulate effectively and flow freely in and out of nursery ponds to maintain healthy conditions for fish. Circulation patterns are largely determined by the strategic placement of inlets and outlets. Since inlets and outlets, by definition, penetrate the liner, they must also be carefully integrated to prevent leaks and function effectively.
Secure seals around every pipe, drain, and penetration are essential for watertight connections to prevent leaks. Based on the liner material, specialized pipe boots, gaskets, and sealing techniques are used during installation. In some cases, custom pipe boots are needed.
Try This: Plan for proper liner integration with inlet and outlet structures early in the design phase. The liner specialists at BTL Liners can help you determine the most appropriate sealing methods for your design.
