Equipment and systems for aquaculture

Abstract

The present invention relates generally to systems and apparatus for the farming of aquatic crustacean and fish species.

Description

[Technical Field]

[0001] The present invention relates generally to systems and apparatus for the growing of aquatic crustacean and fish species. [Background technology]

[0002] The increasing demand for lobster, fish, and related aquatic species has created a need for improved techniques in aquaculture to provide a reliable source of stock. In addition to the need for such techniques, there is an increasing demand for sustainability from fisheries and those involved in aquaculture. This not only protects breeding material and preserves the environments in which it lives, but also increases economic returns for fisheries and the industry as a whole.

[0003] Aquaculture of crustaceans and other marine species is based on broadly similar principles, although the specific equipment used and procedures followed may vary from species to species and depend on other requirements.

[0004] For example, the development of aquatic crustaceans involves various stages that involve successive molting cycles and subsequent transitions through morphological changes. For example, the successful production of lobsters through the larval stage depends on the success of each molting cycle, which is strongly related to the conditions under which the broodstock lobsters are kept.

[0005] Hatchery design and features to ensure successful cultivation of lobsters and other aquatic species include the shape and design of the containers in which they are held, as well as the quality and cleanliness of the water. Planktonic criesels are typically used to rear lobster larvae, and small-scale criesels are often used. These systems are often very useful as laboratory vessels. Drawbacks of previous criesel designs for commercial applications include the inability to scale the system while maintaining favorable hydrodynamics. Factors such as the buoyancy of the larvae and their feed and their interactions within the culture vessel are critical. Additionally, shear generated by water flow must be minimized to reduce physical damage and mortality to the larvae.

[0006] The present invention seeks to address some of the shortcomings of prior art devices and systems in the field of aquaculture. Summary of the Invention

[0007] The present invention is based (in part) on the discovery that the survival rate of lobster larvae can be increased by designing a container (and a system incorporating the container) with specific parameters, including the hydrodynamics and water quality of the culture water. The present invention allows for increased survival of juvenile forms and development of the animals beyond the initial juvenile forms.

[0008] According to a first aspect of the present invention, there is provided a recirculating aquaculture system (RAS), comprising: (i) a drum filter; (ii) a dirty sump, biological filtration sump, or bubble bead filter; (iii) at least one UV light disinfection device; (iv) a foam separator with an ozone injection device or a separate ozone injection device; (v) at least one ozone contact sump or equalization tank having a volume equal to or greater than the volume of the larval rearing tank; (vi) optionally, at least one degasser; (vii) an activated carbon filter; (viii) a bag filter; (ix) optionally, at least one secondary UV light ozone destructor; (x) at least one larval rearing (or incubation) tank with a volume of at least approximately 10,000 L; A recirculating aquaculture system (RAS) is provided, comprising:

[0009] In one embodiment, the aforementioned RAS is characterized in that features (i)-(x) are in fluid contact with the flow of seawater through the system from features (i)-(x) in that order.

[0010] In one embodiment, the aforementioned RAS is characterized in that fresh seawater is introduced into the system at a degasser.

[0011] In one embodiment, the aforementioned RAS is characterized in that fresh seawater is introduced into the system from at least one ozone contact tank or water conditioning tank having a volume of about 10,000 L or more.

[0012] In a further aspect, the present invention provides a method for pretreating seawater for rearing aquatic larvae, comprising: (i) a foam separation step; (ii) an ozone treatment step; (iii) activated carbon filtration; (iv) a UV light sterilization step; (v) UV light ozone destruction step and The present invention provides a method for pre-treating seawater, comprising:

[0013] According to another aspect of the present invention, there is provided a larvae rearing (or culture) tank having a volume of about 10,000 L or more, the culture tank being a substantially circular tank and featuring a water inlet pipe (1) that is substantially centrally located, extends above the tank's water line, and terminates near the bottom of the tank, having an outer surface exposed to the tank water and an internal pipe cavity (2), a conical mesh sleeve (3) attached to the upper surface of the pipe outer surface, the conical mesh sleeve (3) being secured to the pipe below the surface and extending outward above the tank's water line, and a conical sleeve (4), which may be mesh or solid, also attached to the lower surface of the pipe outer surface, the conical sleeve (4) being secured to the pipe below the surface and extending outward toward the tank base below the tank's water line, the internal pipe cavity maintaining a constant supply of seawater toward the base of the tank.

[0014] In one embodiment, the water inlet pipe (1) features both an inner pipe cavity (2) and an outer pipe cavity (5), said outer pipe cavity housing at least one inlet water supply line (6) that allows additional seawater to enter the tank from above the surface of the tank.

[0015] In yet a further aspect, the present invention provides a water circulation assembly for an aquaculture tank, the assembly featuring a water inlet pipe (1) extending above the tank's water line and terminating near the bottom of the tank, the water inlet pipe (1) having an outer surface exposed to the tank water and an inner pipe cavity (2), the upper surface of the pipe outer surface having attached thereto a conical mesh sleeve (3) secured to the pipe below the surface and extending outward above the tank's water line, and the lower surface of the pipe outer surface also having attached thereto a conical mesh or solid sleeve (4), which may be mesh or solid, the conical sleeve (4) secured to the pipe below the surface and extending outward below the tank's water line towards the tank base.

[0016] In one embodiment, referring to the water circulation assembly, the water inlet pipe (1) features both an inner pipe cavity (2) and an outer pipe cavity (5), said outer pipe cavity housing at least one inlet water supply line (6) that allows additional seawater to enter the tank from above the surface of the tank.

[0017] The water in the tank moves about 5-10cm -1 The curved configuration of the tank in the area where the floor meets the sides results in typical flow velocities of approximately 2-5 cm s -1 The water flow is taken in vertically to the side of the tank, and the tapered section of the wall near the surface is about 0.5-2 cm s -1The central water supply pipe captures a water flow that returns toward the center of the tank at a velocity of 0.01 sq. m. The conical sleeve on the central water supply pipe facilitates water movement back toward the tank floor. The water movement within the culture vessel is a donut-shaped configuration fixed around the centrally located water inlet pipe. Features provided by this culture vessel that are useful for culturing negatively buoyant planktonic larvae include gentle flow, minimal shear, and approximately 0.5-1.0 times per hour of culture vessel inversion, which maintains a uniform distribution of larvae and neutrally buoyant food particles within the water column. In this regard, those skilled in the art will appreciate that the present invention is particularly advantageous for aquatic animal species that do not actually swim or feed on food sources, such as planktonic larvae. That is, the present invention provides an environment in which the water flow and turbulence within the tank are maintained to maximize the probability that larvae will physically contact (i.e., "collide") with a food source, while at the same time preventing the turbulence and sheer force of the water flow from physically damaging the very delicate larvae. In certain embodiments, the tank further features a set of (e.g., 12) replaceable perforated screens positioned around the periphery of the top surface of the culture tank to also enhance passive feeding and waste removal capabilities. These screen sets are manufactured with a hole size range of approximately 2.0 to 6.0 mm. In a further embodiment, the configuration of the water outlet end of the centrally located inlet pipe (terminating at the base of the tank) is designed to further ensure a smooth transition from vertical to horizontal water flow while minimizing turbulence and shear forces beyond the periphery of the central water pipe conical sleeve, as described in further detail below. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a schematic diagram of a RAS according to one embodiment of the present invention.

[0019] [Figure 2] FIG. 2 is a schematic diagram of a RAS according to one embodiment of the present invention.

[0020] [Figure 3] FIG. 2 is a schematic diagram of a RAS according to one embodiment of the present invention.

[0021] [Figure 4] FIG. 1 is a photograph of one embodiment of a larvae rearing (or culture) tank according to the present invention.

[0022] [Figure 5] FIG. 1 is a photographic representation of an embodiment of a substantially centrally located water inlet pipe within an embodiment of a larvae rearing (or culture) tank according to the present invention.

[0023] [Figure 6] FIG. 1 is a schematic diagram of an embodiment of a substantially centrally located water inlet pipe extending within an embodiment of a larvae rearing (or culture) tank according to the present invention.

[0024] [Figure 7] FIG. 1 is a schematic diagram of an embodiment of a substantially centrally located water inlet pipe extending within an embodiment of a larvae rearing (or culture) tank according to the present invention.

[0025] [Figure 8] FIG. 1 is a schematic diagram of an embodiment of a substantially centrally located water inlet pipe extending within an embodiment of a larvae rearing (or culture) tank according to the present invention.

[0026] [Figure 9] FIG. 1 is a top view of a 10,000 L culture tank according to one embodiment of the present invention.

[0027] [Figure 10] FIG. 1 is a side view of a 10,000 L culture tank according to one embodiment of the present invention.

[0028] [Figure 11] FIG. 10 shows an Excel spreadsheet of water quality and conditions for various embodiments of the system according to the present invention.

[0029] [Figure 12]1 shows a replaceable perforated screen according to the present invention;

[0030] [Figure 13] FIG. 1 illustrates a replaceable perforated screen according to one embodiment of the present invention.

[0031] [Figure 14] FIG. 1 illustrates a replaceable perforated screen according to one embodiment of the present invention.

[0032] [Figure 15] FIG. 1 illustrates a replaceable perforated screen according to one embodiment of the present invention.

[0033] [Figure 16(A)] 1 is a diagram showing the configuration of a standpipe according to the present invention. FIG. [Figure 16(B)] 1 is a diagram showing the configuration of a standpipe according to the present invention. FIG.

[0034] [Figure 17(A)] 1 is a diagram showing the configuration of a standpipe according to the present invention. FIG. [Figure 17(B)] 1 is a diagram showing the configuration of a standpipe according to the present invention. FIG.

[0035] [Figure 18(A)] FIG. 2 is a cutaway view of a standpipe of the present invention. [Figure 18(B)] FIG. 2 is a cutaway view of a standpipe of the present invention.

[0036] [Figure 19(A)] FIG. 1 shows a standpipe ("substantially centrally located water inlet pipe (1)") configuration of the present invention. [Figure 19(B)] FIG. 1 shows a standpipe ("substantially centrally located water inlet pipe (1)") configuration of the present invention.

[0037] [Figure 20(A)] 1 illustrates a standpipe configuration of the present invention. FIG. [Figure 20(B)] 1 illustrates a standpipe configuration of the present invention. FIG.

[0038] [Figure 21] FIG. 1 illustrates a tank design according to the present invention.

[0039] [Figure 22] FIG. 1 illustrates a tank design according to the present invention.

[0040] [Figure 23] FIG. 1 illustrates a tank design according to the present invention.

[0041] [Figure 24] FIG. 1 illustrates a radial diffuser tank plug according to the present invention.

[0042] [Figure 25] FIG. 10 shows a sleeve that positions the radial diffuser plug and attaches it to the standpipe device.

[0043] [Figure 26] FIG. 10 shows a water flow diffuser at the end of a standpipe configuration when a solid cone is used.

[0044] [Figure 27] FIG. 1 shows a cradle design configuration for a tank according to the present invention.

[0045] [Figure 28] 1 illustrates a base plate design configuration for a tank according to the present invention. FIG.

[0046] [Figure 29] FIG. 1 is an exploded view of the standpipe configuration of the present invention when a solid cone is used. DETAILED DESCRIPTION OF THE INVENTION

[0047] Detailed Description of the Invention The RAS of the present invention is equipped with a drum filter that allows for the removal of large organic particulate waste from the culture tank. In one embodiment, the drum filter can filter the contents of the culture tank at a rate of approximately 100-200 L / min, or 144,000 L to 288,000 L / 24 hours. The drum filter can be fitted with a variety of appropriately sized screens (20 μm to 60 μm) designed for use with seawater. Filters suitable for this purpose can be purchased, for example, from Faivre (France). The non-particulate wastewater can then be transported, for example, by gravity flow techniques, to a dirty sump and a treatment sump, which may be a bubble bead filter or a biological filtration sump. The wastewater is either processed through the remainder of the RAS to become recycled water or overflows for disposal. The amount of overflow is adjusted by the input of new water minus losses embodied in particulate disposal from the drum filter or foam separator. The recycled water can be treated under UV light disinfection. This can include a single-stream or dual-stream UV light disinfection system. Following UV light disinfection of the recirculating water stream, the system may optionally include flowing the water through one or two bubble bead filters. The filter(s) may be used to capture any remaining particulate matter larger than about 50 μm. Such filters are available, for example, from AST Acquaculture Systems Technologies (USA). In a preferred embodiment, the use of bubble bead filters is desirable only if a dirty sump (i.e., a non-biological filtration sump) is utilized within the RAS. The primary reason is that, although a bubble bead filter can also provide biological filtration, when used in conjunction with a biological filtration sump, it may provide the additional benefit of removing soluble waste materials such as ammonia from the water stream.

[0048] The water stream from the RAS of the present invention can undergo foam separation by passing through UV sterilizer(s) and / or bubble bead filters. Foam separators, such as those available from Aquasonic (Australia), can be used for this purpose. The separator provides further reduction of dissolved organic compounds. Ozone can be introduced at the foam separator using a venturi device attached to the separator, injected at a separate injection point, or injected separately using an ozone reaction chamber. Ozone can increase the oxidation-reduction potential of the water stream, reducing microbial load and increasing the dissolved oxygen content in the water stream. The water stream is then directed through an ozone contact chamber or a water conditioning tank. Ozonation can be performed to achieve disinfection of the recycled water by providing enough ozone to achieve the required oxidation / reduction potential (ORP). An ozone generator from the control unit adjusts the generator output to achieve the desired disinfection ORP, which can be used for this purpose. Optionally, fresh pretreated seawater can be added at this point. Alternatively, new pretreated seawater may be added in the next stage, which involves passing the water through a degassing tank (deaerator). The degassing step allows for the removal of excess gases, which may include CO2, which may help maintain a higher pH level in the water stream. The water stream may pass through an activated carbon filter and then a bag filter. Before entering the culture tank, the water stream may undergo UV light ozone destruction to ensure that the ORP is within the required range.

[0049] In one embodiment, the water flow may have the following parameters as it enters the culture tank: a temperature between about 23 and 32°C, such as a temperature of about 24, 25, 26, 27, 28, 29, 30, or about 31°C, or a temperature within a range between any two of the foregoing numbers; a pH of about 7-10, such as a temperature of about 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, or about 9.9, or a pH in the range between any two of the above numbers; at an oxygen % of about 70-140%, such as about 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, or about 135%, or at a temperature ranging between any two of the above numbers; a salinity (ppt) of approximately 25, 26, 28, 29, 30, 31, 32, 33, 34, 35, or 36, or a range between any two of the above numbers; an ORV (mV) of about 280-450, such as about 285, 290, 295, 300, 305, 310, 315, 320, 325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, 380, 385, 390, 395, or about 400, or a range between any two of the above numbers; Alkalinity (meg / L), such as about 1, 1.3, 1.5, 1.7, 1.9, 2.1, 2.3, 2.5, 2.7, 2.9, 3.1, 3.3, 3.5, 3.7, 3.9, or about 4.1, or a range between any two of the above numbers; Calcium (ppm), such as about 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or about 500, or a range between any two of the foregoing numbers; and Magnesium (PPM), such as about 900, 930, 960, 1000, 1050, 1110, 1130, 1150, 1170, 1180, 1200, 1250, 1270, 1290, 1300, 1310, 1320, 1330, 1340, or about 1350, or a range between any two of the above numbers

[0050] The temperature conditions listed above are most suitable for tropical spiny lobsters such as the Japanese spiny lobster (Panulirus ornatus). For other non-tropical species, the optimum temperature may be lower, for example, about 18 to about 23°C.

[0051] Figure 1 illustrates an RAS system according to one embodiment, in which water enters a dirty sump, is pumped, and then split through two UV light sterilizers and corresponding bubble bead filters. The flow then recombines and enters a foam separator, where ozone can be injected through a venturi. Water overflows from the separator into an 1,800 L ozone sump, where it has contact time at elevated ORP (oxidation / reduction potential) levels, before overflowing again into a 10,000 L water conditioning tank. Ozonation is controlled using an ozone generator. Water from the water conditioning tank is pumped into the top of the deaerator, through an activated carbon filter, a bag filter (100 μm), and a secondary UV light ozone destroyer (ozone reduction), before being pumped into the larvae tank (or culture tank). Fresh water to the system enters through the deaerator.

[0052] Figure 2 shows another embodiment of the RAS system, in which water flows from the tank through a drum filter into a 1,000-liter dirty sump (biological filtration sump), which doubles as a biofilter and contains biofilter media. Water from the dirty sump is pumped through a UV light sterilizer into a foam separator, where it can be ozonated through a venturi. The water overflows from the separator into one 900-liter ozone sump and is then baffled into another 900-liter sump to increase contact time and maintain an ORP above 710 mV for 10 minutes. Ozonation is controlled using an ozone generator. The ozonated water then flows into a 10,000-liter clean sump (water conditioning tank), where it is pumped through a deaerator, a carbon filter, a secondary UV light ozone destroyer, and a bag filter (100 μm) before being pumped into the larvae tank (or culture tank). New water to the system goes into the clean sump / water conditioning tank.

[0053] Figure 3 shows another embodiment of the RAS system, in which water from two larvae tanks flows through a drum filter and into a 2,000 L dirty sump that doubles as a biofilter. Water from the dirty sump is pumped through a UV light sterilizer and into a foam separator, where it can be ozonated through a venturi. The water overflows from the separator into one 1,800 L ozone sump and then baffled into another 1,800 L sump to increase contact time and maintain ORP. Ozone treatment is provided by a water-cooled generator. The ozonated water overflows into a 15,000 L clean sump and then into a 10,000 L clean sump. From the second clean sump, water is pumped into a deaerator, then through a carbon filter, a bag filter (100 μm), and a secondary UV light ozone destructor before being split into two larval tanks (culture tanks). New water to the system enters the second clean sump (water conditioning).

[0054] To enhance larval and feed interaction, all three of the aforementioned systems (i.e., Figures 1, 2, and 3) have pneumatically controlled three-way Burkert valves that return water to the dirty sump in Figure 1, the clean sump in Figure 2, and the second clean sump in Figure 3. Simultaneously, the Burkert valve at the outlet of the 10,000 L larval tank (culture tank) shuts off to maintain water in the tank, retaining as much water as possible within the system and essentially stopping water flow into the culture vessel for the period the Burkert valve is activated. The timer controlling the Burkert valve also controls the lighting, turning it off when there is no flow into the tank, preventing larvae from pooling at the surface and encouraging them to sink to the bottom of the tank along with the food. As a fail-safe measure against the delivery of ORP higher than the desired ORP, a secondary UV light ozone destructor is placed in all three systems just before the water enters the larval / culture tank. The secondary UV is activated by a Foxboro ORP probe placed in each larva / culture tank or can be switched on manually.

[0055] In one embodiment, the larvae rearing (or culture) tanks referred to herein are based on Kriesel tanks, which provide a slow, circular flow of water with minimal internal hardware to prevent injury to resident animals by the pump or the tank itself. The tank has no sharp angles around its sides, keeping housed animals away from piping. Water moving into the tank provides a gentle current that keeps resident animals suspended. Water exits the tank through a screen that prevents animals from being drawn into the pump's intake or overflow line. An example of a Kriesel tank configuration suitable for the system of the present invention is shown in Figures 9 and 10 and has a capacity of 10,000 L. Traditional Kriesel tanks are based on much smaller volumes and often feature two downflow inlets on either side of the tank, which provide gravity to create two vortices within the tank. The tanks disclosed herein are specifically designed from Kriesel tank systems of approximately 10,000 L or larger, requiring water changes in up to one culture vessel every 24 hours.

[0056] Figure 4 shows a 10,000 L tank with a central 50 mm standpipe (referred to herein as the "substantially centrally located water inlet pipe") in the tank floor. As the water exits the inlet, a grooved (or conical) fixture converts vertical flow to horizontal, minimizing shear stress on the larvae. Due to the tank shape, water circulates around the central standpipe in a donut shape, aided by conical mesh sleeves at the top and bottom of the inlet (see Figure 5). Water also flows counterclockwise around the tank due to the inclined vanes on the vaned pipe supports (Figure 26). Excess water exits the tank through 12 circumferential screens on the top surface of the tank and into a peripheral trough (also seen in Figures 9 and 10), exiting through a screen corresponding to the sleeved standpipe to maintain the water level and further draw water from all screens. The trough has a 13 mm ring, or notch line, with 12 4 mm 90-degree spouts designed to prevent food from settling in the trough. The standpipe is fitted with a bottom slotted sleeve to allow wastewater to be drawn from the floor of the trough. Water and waste food are siphoned up the inside of the sleeve and through the top of the standpipe to the circumferential trough and drum filter (50 μm Hydrotech) and into the "dirty sump." Variations on a substantially centrally located water inlet pipe are shown in Figures 6-8. In certain embodiments, the base of the central 50 mm standpipe is fitted with a floor cone to help reduce shear (improving the hydrodynamic quality of the culture tank), as shown in Figure 11.

[0057] Figures 12, 13, 14, and 15 show interchangeable perforated screens positioned around the periphery of the top surface of the culture tank to provide passive feed and waste removal capabilities. The screen sets are manufactured with a pore size range of approximately 2.0 to 6.0 mm. The advantage of a variable pore size range is that screens can be selected based on the growth size of the lobster larvae. The idea is that larger feed compositions (e.g., in pellet form) can be used during lobster growth, and therefore larger screen sizes are preferred to allow the passage of any unconsumed feed without clogging the screening material while still maintaining animals of appropriate size within the 10,000 L culture vessel. The screens are also preferably interchangeable to facilitate cleaning and maintain the desired water exchange within the 10,000 L culture vessel.

[0058] Figure 16(A) shows a standpipe (referred to herein as a "substantially centrally located water inlet pipe") configuration that, in use, extends above the tank's water level line (as shown in Figure 4), terminates approximately near the bottom of the tank, and has a water inlet pipe (1) with an outer surface exposed to the tank, with conical sleeves (3, 4) attached to the upper and lower surfaces of the pipe outer surface that are mesh (although the lower sleeve 4 may be solid). If mesh, the mesh size may be in the range of about 2.0-10.0 mm.

[0059] Figure 16(B) shows the underside of a standpipe with a radial diffuser tank plug (7) positioned at the end of the water inlet pipe toward the tank base. The radial diffuser tank plug secures the standpipe to the tank floor and ensures that water terminating from the centrally located pipe meets the bulk tank water in a smooth transition from vertical to horizontal water flow while minimizing turbulence and shear forces beyond the periphery of the conical sleeve (4). It can thus be seen that the sleeve (4) and plug (6) work together to achieve this smooth transition. In one embodiment (see Figure 18(b)), the radial diffuser tank plug (7) can be positioned to extend a distance of approximately 30 mm to 70 mm beyond the radius into the conical sleeve (4) to allow water to flow unimpeded from the standpipe and optimize a smooth transition from vertical to horizontal water flow while minimizing turbulence at the conical sleeve interface. By varying the amount the standpipe is inserted into the vaned pipe support sleeve (10) shown in Figure 25. A depiction of the radial diffuser tank plug separated from the standpipe is shown in Figure 24. In this embodiment where the conical sleeve (4) is solid (e.g., using HDPE), the standpipe (1) can also include a water flow diffuser (11) (in addition to the radial diffuser plug) as shown in Figure 26. In this embodiment, the outer cavity accommodates a single inlet water supply line.

[0060] Figure 18(B) is a cutaway view of a standpipe with a lower conical solid sleeve attached and a radial diffuser tank plug. This depiction shows an embodiment in which the standpipe (1) is comprised of an inner pipe cavity (7) and an outer pipe cavity (8). The inner pipe cavity serves as the central source of seawater delivery into the tank. In certain embodiments where the conical sleeve (4) is meshed, the outer cavity houses at least two inlet water supply lines to provide flow to the outer surface of the mesh sleeve to prevent the accumulation of feed particles and maintain a clean surface. In certain embodiments, the inner cavity hoses 2, 3, or 4 water supply lines to ensure all areas of the mesh sleeve remain particle-free. In certain embodiments, the lower mesh cone (4) is fitted with an internal circular water pipe (12) designed to spray water (under pressure) into and across the mesh to ensure it does not get dirty or clogged, as shown in Figure 16(B).

[0061] Figure 19(A) shows a configuration in which the inner and outer supply lines are connected via a Y-junction connector. It will be appreciated that the water supplies from both the inner and outer cavities of the standpipe terminate at the bottom of the tank.

[0062] Figure 21 shows the time from approximately 0.5 to 2 cm·s -1 Figures 22 and 23 show an embodiment of a tank design featuring a tapered upper section on the wall near the surface, which has been observed to provide the added benefit of maintaining flow across the surface back toward the center of the tank at a velocity of 100 psi. Figures 22 and 23 show another configuration of the tank design having a tapered upper section with openings to accommodate the replaceable perforated screen shown in Figures 12-15.

[0063] In order that the present invention may be readily understood and put into practice, certain preferred embodiments will now be described by way of the following non-limiting examples.

[0064] The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference in their entirety.

[0065] The citation of any reference herein should not be construed as an admission that such reference is available as "Prior Art" to the instant application.

[0066] Throughout this specification, the objective has been to describe preferred embodiments of the present invention without limiting the invention to any one embodiment or particular collection of features. Accordingly, those skilled in the art will appreciate in light of this disclosure that various modifications and changes can be made in the particular embodiments illustrated without departing from the scope of the present invention. All such modifications and changes are intended to be included within the scope of the appended claims.

Claims

1. 1. A larvae rearing (or culture) tank having a volume of about 10,000 L or more, the culture tank being a substantially circular tank and characterized by a substantially centrally located water inlet pipe (1) that extends above the tank's water line and terminates substantially near the bottom of the tank, the water inlet pipe (1) having an outer surface exposed to the tank water and an internal pipe cavity (2), the upper surface of the pipe outer surface having a conical mesh sleeve (3) attached thereto and secured to the pipe below the surface and extending outward above the tank's water line, the lower surface of the pipe outer surface also having a conical sleeve (4), which may be mesh or solid, attached thereto and secured to the pipe below the surface and extending outward towards the tank base below the tank's water line, the internal pipe cavity maintaining a constant supply of seawater towards the base of the tank.

2. 2. The tank according to claim 1, characterized in that the water inlet pipe (1) features both an inner pipe cavity (2) and an outer pipe cavity (5), the outer pipe cavity accommodating at least one inlet water supply line (6) that allows additional seawater to enter the tank from above the face of the tank.

3. 3. A tank according to claim 1 or claim 2, wherein both said conical sleeves (3, 4) are mesh.

4. 3. The tank according to claim 1 or 2, wherein the conical sleeve (4) is solid.

5. 2. The tank according to claim 1, wherein the standpipe of the centrally located water inlet pipe (1) further comprises a radial diffuser tank plug (7) located at the end of the water inlet pipe towards the tank base.

6. 2. The tank of claim 1, wherein the radial diffuser tank plug (7) secures the standpipe to the tank floor and ensures that the water terminating from the centrally located pipe (1) meets the bulk of the tank water in a smooth transition from vertical to horizontal water flow while minimizing turbulence and shear forces beyond the periphery of the conical sleeve (4).

7. 1. A water circulation assembly for an aquaculture tank, the assembly comprising: a water inlet pipe (1) extending above the tank's water line and terminating near the bottom of the tank, the water inlet pipe (1) having an outer surface exposed to the tank water and an inner pipe cavity (2); a conical mesh sleeve (3) attached to the upper surface of the pipe outer surface, the conical mesh sleeve (3) being secured to the pipe below the surface and extending outward above the tank's water line; and a conical mesh or solid sleeve (4), which may be mesh or solid, attached to the lower surface of the pipe outer surface, the conical sleeve (4) being secured to the pipe below the surface and extending outward below the tank's water line towards the tank base.

8. 8. A water circulation assembly according to claim 7, characterized in that the water inlet pipe (1) features both an inner pipe cavity (2) and an outer pipe cavity (5), the outer pipe cavity accommodating at least one inlet water supply line (6) that allows additional seawater to enter the tank from above the face of the tank.

9. 9. A water circulation assembly according to claim 7 or claim 8, wherein both said conical sleeves (3, 4) are mesh.

10. 9. A water circulation assembly according to claim 7 or claim 8, wherein the conical sleeve (4) is solid.

11. 8. The water circulation assembly of claim 7, wherein the standpipe of the centrally located water inlet pipe (1) further comprises a radial diffuser tank plug (7) located at the end of the water inlet pipe towards the tank base.

12. 8. The water circulation assembly of claim 7, wherein the radial diffuser tank plug (7) secures the standpipe to the tank floor and ensures that the water terminating from the centrally located pipe (1) meets the bulk of the tank water with a smooth transition from vertical to horizontal water flow.

13. 1. A recirculating aquaculture system (RAS), comprising: (i) a drum filter; (ii) a dirty sump, a biological filtration sump, or a bubble bead filter; (iii) at least one UV light disinfection device; (iv) a foam separator with an ozone injection device or a separate ozone injection device; (v) at least one ozone contact sump or equalization tank having a volume equal to or greater than the volume of the larvae rearing tank; (vi) optionally at least one degasser; (vii) an activated carbon filter; (viii) a bag filter; and (ix) optionally, at least one secondary UV light ozone destructor; and (x) at least one larvae rearing (or culturing) tank having a volume of about 10,000 L or more according to any one of claims 1 to 6; RAS equipped with.

14. 14. The RAS of claim 13, wherein features (i) through (x) are in fluid contact with a flow of seawater through the system from (i) through (x) in that order.

15. 15. The RAS of claim 13 or 14, wherein fresh seawater is introduced into the system at the degasser.

16. 15. The RAS of claim 13 or 14, wherein fresh seawater is introduced into the system from at least one ozone contact tank or water conditioning tank having a volume of about 10,000 L or more.

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