CULTIVATION TANK FOR AQUATIC ORGANISMS

Abstract: In a tank (1) for the incubation or cultivation of aquatic organisms, there is a supply pipe (6) for water, and an outlet pipe for water, excess feed, excrement, dead eggs and the like. The outlet pipe (13) from the tank (1) has an intake area close to the bottom (3) of the tank, where this intake area comprises a suction unit (24a, 24b) for particle substances that are heavier than the water in the tank (1). The suction unit (24a, 24b) comprises one or more suction arms (24a, 24b) with an extended range since the suction arms (24a, 24b) are positioned so that they can move along the bottom at least part of the time water is being emptied. The suction arm or suction arms (24a, 24b) can move to cover an area that approximately corresponds to the shape and size of the bottom (3).

Description: Cultivation tank for aguatic organisms The invention concerns a device that is a cultivation tank for aquatic organisms, as described in the introduction to Claim 1. Fish tanks are presently either made of plastic, steel, or concrete in a number of designs. The removal of excess feed, excrement and the like is usually done by emptying large volumes of water from the tank to allow technical staff to brush the bottom of the tank clean. If the water outlet and supply is forced to flow by means of a current, there is a better degree of self-cleaning. This however requires considerable amounts of water to be supplied. Marine fish larva such as cod, turbot, halibut and plaice are too sensitive for such strong water current. Thus the cleaning of tanks for these species has to be done manually by technical staff vacuuming the bottom with a syphon that has a suitable nozzle fitted to the end. This operation is excessively time consuming. In cases where the water is recirculated it is disadvantageous to have a strong water current flowing through the tank. The main objective of the present invention is to design a fish cultivation tank that is hygienic, with restricted water motion in the tank and where the required cleaning work is minimal. This has been realized by a fish cultivation tank designed in accordance with the characterizing part of Claim 1. Other advantageous features of the invention are evident from the subsidiary claims. The invention will now be described by means of one example of a design, referring to the enclosed drawings, where Fig. 1 shows a first, preferred design in accordance with the present invention. Fig. 2 shows a detail of a second means of designing a water control mechanism for a device in accordance with the present invention, and Fig. 3 shows the cog in Fig. 1 in detail. Reference is first made to Fig. 1, that shows a cultivation tank, generally indicated as 1, with a wall, or walls 2 and a bottom 3. The bottom 3 is essentially circular, and the wall 2 is preferably cylindrical or conical. The bottom can for example be profiled in towards the centre. The tank 1 can be covered by a top. The tank 1 has a supply pipe 6 for water, and an external outlet pipe 7 for water and residue. The described fish tank 1 also has a rotating dredge unit 20 that uses suction or scraping to keep the bottom 3 clean of excess feed, excrement, dead eggs and other material lying on the bottom. The rotating suction dredge unit 20 comprises at least one suction arm, preferably two suction arms 24a, 24b. Suction arms 24a, 24b can be fitted with rubber scrapers or brushes to make the cleaning more efficient. The rotating suction dredge unit 20 is located in a recess 22 in the centre of the tank, an advantageous design would combine the recess 22 together with the outlet. At the upper end of the suction dredge unit 20, a cog 19b is located concentrically, which can be seen in greater detail in Fig. 3. The cog 19b has sloping teeth that engage in an equivalent cog 19a. Cog 19a is notrotatable in relation to the bottom 3, but can be moved vertically in relation to it. Cog 19a is connected to a weight 18 and a float 14. Cogs 19a and 19b are designed like those found in standard ballpoint pens. The triangular teeth are tapered to a point. At least one of cogs 19a, 19b has teeth with a side that is parallel to the direction of motion when there is a rising or falling movement. Cogs 19a, 19b are coordinated so that their teeth become engaged next time there is falling motion. Thus the two cogs 19a, 19b rotate in accordance with each other. This is done by the teeth in the cogs being at different distances, and/or are located asymmetrically to each other. The number of teeth and the ratio between the number of teeth on the respective cogs 19a, 19b help to determine the size of the sector that can be covered each time there is falling motion. An alternative to this is using a double cog, or a mechanism designed like a revolver, with a spring-loaded barb or (claw) that engages the cog. This is positioned so that the point of engagement moves each time the weight/float reaches its upper position. Water that is sucked through the dredge unit 20 runs through the outlet pipe 7. The outlet pipe is shaped so that it acts as a syphon every time the water in the tank comes above the level limit 12. When this happens, the syphon pipe 9 that is connected to the outlet pipe starts to lead the water out of the tank. The flow of outgoing water stops each time the syphon sucks in air through an air tube 10 which has a valve 11 that opens when the water level comes under the valve 11. This means that there is an outflow of water from the tank 1 at intervals. It is advantageous if the outlet pipe 7 is fitted with a tap or similar means of controlling ' the rate of emptying. In Fig. 2 a design is shown where the water level control mechanism is located inside the tank 1. This design means that there is no need to have a valve in the air tube, however the air inlet 11 in the tank must be fitted with a sieve so that larva are not drawn into it. The syphon pipe 9 is placed centrally in the tank, as shown in Fig. 2, together with the weight/float that is enclosed by a casing. It is also possible to control the emptying of large quantities of water by means of upper and lower water level switches combined with a magnetic valve, the method required here is already known (not illustrated). While the water is being emptied, the suction arms 24a, 24b on the dredge unit 20 start to rotate above a limited section of the bottom 3. The suction dredge unit 20 is driven by the falling water level forcing weight 18 and float 14 to sink making the inclined cogs 19a, 19b move in relation to each other, cog 19b also moves in relation to the bottom 3. Other approaches are to drive the dredge unit with an electric motor or a screw/gear mechanism driven by the incoming water. The water exchange could either be done at intervals or continually. Rotation must take place between the suction unit and the bottom of the tank, so that it is possible to have a suction unit that remains stationary while the bottom of the tank rotates. Should live larva come to the bottom 3, they can be forced upwards by carefully allowing water with highersalinity than the rest to flow into the tank through a tap 21. This should preferably be done just before emptying. An alternative design is mounting the suction unit upside down under a perforated plate. It is also feasible that the suction unit is fitted with a fine grille, brush or something similar that will chase away any live larva that comes too close to the suction unit. Another means of chasing away such larva is an electronic barrier around the suction unit. It would be an advantage if the tank 1 was equipped with a biological filter, or a protein trap. This could consist of a strainer tube 17, filter chamber 15, riser/aerator 16 and [spreader pipe] the weight 18. By forcing air into the lower part of the riser 16, water will be drawn into the riser 16 and out of the spreader pipe [17] 8.. This will be effected by water being sucked in through the strainer tube 17 and led into the filter chamber 15. The function of the biofilter will be the removal of ammonium (NH ) and ammoniac (NH ) from the water. SUBSTITUTE SHEET

Claims: Claims: 1. A device with a tank (1) for the incubation or cultivation of aquatic organisms, where the tank (1) has a supply pipe (6) for water, and an outlet pipe (13) for water, excess feed, excrement, dead eggs and the like, with an intake area close to the bottom (3) of the tank, where the intake area comprises a suction unit (24a, 24b) essentially for particle substances with a specific weight that is heavier than the water in the tank (1), c h a r a c t e r i z e d by the suction unit (24a, 24b) comprising one or more suction arms (24a, 24b) with an extended range since the suction arms (24a, 24b) are positioned so as to be moved along the bottom for at least part of the time water suction is being carried out. 2. Device as claimed in Claim 1, c h a r a c t e r i z e d by the suction arm or suction arms (24a, 24b) that when in motion cover an area approximately corresponding to the shape and size of the bottom (3). 3. Device as claimed in Claims 1-2, c h a r a c t e r i z e d by there being an electric motor and/or water screw in the supply pipe (6) to move the suction arms. .4. Device as claimed in Claims 1-2, c h a r a c t e r i z e d by the suction unit (20) being connected at its upper end to a first cylindrical cog (19b) that is located concentrically, and that a second moveable cog (19a), with a different number of teeth than the first cog (19b), is connected to a float (14) and a weight (18), where the teeth in the cogs (19a, 19b) are pointed so that they engage thereby rotating the suction unit (20) in relation to the bottom (3) when the falling water level makes the float (14) and the weight (18) move downwards, thereupon moving the second cog (19a) in an axial direction. 5. Device as claimed in Claims 1-4, c h a r a c t e r i z e d by the outlet pipe (7, 9) that leads from an upper point (12), that corresponds to the maximum level of water in the tank (1), down to an outlet (13) below the minimum level of water in the tank (1), where the outlet pipe (7) contains an air tube (10) with an inlet (11), this inlet (11) is to correspond to the lowest level of water in the tank (1), and is open to the surrounding air when the level of water in the tank (1) and in the pipe (7, 9) is below the inlet (11). 6. Device as claimed in Claims 1-5, c h a r a c t e r i z e d by there being an upper level switch which corresponds to the upper level of water in the tank (1), and a lower level switch corresponding to the minimum level of water in the tank (1), where the level switches combined with a magnetic valve have the function of controlling the emptying of the tank (1). 7. Device as claimed in some of the above claims, c h a r a c t e r i z e d by there being a pump connected to the outlet pipe (7, 9). 8. Device as claimed in some of the above claims, c h a r a c t e r i z e d by the suction unit (20) with suction arms (24a, 24b) being positioned under a perforated plate. 9. Device as claimed in some of the above claims, c h a r a c t e r i z e d by the suction unit (20) having a fine grille and/or an electric barrier to chase away live larva.

Inventors: JOERGENSEN LEIF, JOERGENSEN, LEIF
Applicants: SINVENT AS
Application year: 1990
Main classification: A01K63
IPC codes: A01K63