NO20231216A1 - A live fish tank re-circulation arrangement - Google Patents

Description

Technical Field

[0001] The present invention relates to a live fish tank arrangement with an integrated and dedicated water circulation.

[0002] When fish is to be kept in a tank for any significant period it is necessary to circulate water though the tank. The flow of the water ensures a good environment for fish, in particular to supply the fish with oxygen rich water, and it provides the opportunity to treat the water, such as supplying extra oxygen to the water, removing CO2 and filtering out impurities from the water. It is therefore vital to the fish health to ensure a sufficient flow through the fish tank.

Background Art

[0003] Conventionally, the equipment used to provide circulation comprises pipes and pumps that is also used for transferring the fish into and out of the tank, and also lifting the water to a higher level for removal of CO2. The re-circulation system also includes other types of water treatment, such as filtering. This water treatment causes pressure losses in the re-circulation that have to be overcome by the pumps. Moreover, when the same pumps are used for transfer of fish and a huge amount of water, this requires high-capacity pumps, which have a lifting height of about 15m. Typically, the pumps will have an effect of around 60 - 230 kW. When using such a pump for pure re-circulation, it will have to be run at a much lower lifting height than when transferring fish and water. This means that the pump has to operate in a range where it is not very efficient. Consequently, the energy consumption will be substantially higher than what actually is needed to provide the necessary recirculation.

[0004] There exist prior art solutions that uses a pump integrated with the tank. One such solution is described in CN113229185A. Here a circular tank is provided with a centrally arranged sump that is separated from the rest of the tank by a water permeable screen. A circulation pump is arranged within the sump, and pumps water from the sump to a plurality of nozzles that are arranged in a circle along the bottom of the tank.

[0005] Although this solution may work well, it is a very complicated solution where the circulation system takes a lot of space and causes the available space for fish to be significantly smaller than the total volume of the fish tank. It has a large central column containing a circulation pump, and it requires a think bottom to accommodate pipes and various other equipment.

[0006] US4211183A describes another solution for a circular fish tank. It has a central part that is separated from the peripheral part by a mesh. An impeller transports water from the central part via a pipe and over a horizontal plate. From this plate the water runs down and into the tank.

[0007] The central part takes up a large portion of the tank and leaves a very reduced space to the fish. Moreover, the pipe and plate extend to above the water level and will hinder access to the tank from above. It is not a convenient solution for a four-sided tank.

[0008] DE202006006832U1 describes a fish accommodation arrangement with water circulation. It has several chambers, including a fish chamber. Water is flowing from the fish chamber to a sediment chamber, which includes a pump compartment. From the pump compartment the water is pumped via a water distribution unit with gas treatment and back again to the fish chamber. A bio reactor is also included in the arrangement.

[0009] The different units of this arrangement are substantially within a single outer box shape. However, the different units seem to take up a large space, which cannot be used to accommodate fish. Moreover, the water is at one point elevated to above the fish chamber. This increases the building height of the arrangement.

[0010] KR100998799B1 relates to an aquarium for decorative purposes. The aquarium is split into two parts, one main tank and one part which is denoted as a reef. The fish may swim freely between the main tank and the reef. A circulation pump is arranged to circulate the water between the main tank and the reef.

[0011] KR101555973B1 describes a circulation arrangement that is placed outside of the fish tank. It comprises a lower low-pressure chamber and an upper highpressure chamber. A pump pumps the water from the lower to the upper chamber.

As the arrangement is a separate unit from the fish tank, it requires substantial extra space.

Summary of invention

[0012] The present invention has the following objectives:

• Provide the possibility to use a pump having pump characteristics, such as an optimal effect range, suitable for re-circulation at a low lifting height and high flow.

• Limit the required space of the fish tank and the circulation arrangement, so that the required space is as little as possible beyond the space required for the fish tank as such. The invention reduces the amount of pipes and valves in the pump rooms, and it provides the possibility to place pumps inside the water manifold. Consequently, the footprint of the pump rooms is reduced.

• Provide easy access for cleaning and maintenance.

[0013] In a conventional system there is a substantial pressure loss when water has to be pumped through lengths of pipe, a plurality of valves, filters, UV treatment units etc. In the present invention, the screens will contribute to a small pressure loss in the circulation system, but the pressure loss on other parts of the system is negligible.

[0014] This is an important factor that makes it possible to use low-effect pumps in the present invention. A conventional multi-function pump has a low efficiency when used for recirculation. It is difficult to get below an effect of 60 kW when the pump is set to recirculate a water amount of, e.g., 3000 m3/hour. According to the invention a low-effect pump is used, which, e.g., can circulate the same amount of water at an effect of around 6 kW.

[0015] A key feature of the present invention is that the re-circulation arrangement is dedicated to the task of re-circulating. The water will recirculate a short distance and with as little resistance as possible. Any branching off of water for treatment will be done by a different system than the system of the present invention. Thereby the recirculation pumps of the present invention can be run continuously independent of the need for water treatment.

[0016] Other objectives achieved by the invention will be clear from the description below.

[0017] The above objectives are met by the arrangement according to claim 1.

Detailed description of the invention

[0018] The figure shows an embodiment of a circular fish tank with circulation arrangement according to the invention in a cross-sectional view.

[0019] Referring to the figure, this shows in a preferred embodiment, a circular fish tank 1, having a bottom 2 and an encircling wall 3. The bottom 3 is preferably inclined towards a centre thereof.

[0020] “Circular” in this context is meant to cover any fish tank that is substantially circular. It may be oval or many-sided, such as hexagonal or octagonal.

[0021] The fish tank has a central column 4, which comprises a water permeable partition or screen 13 that keeps the fish on the outside of the column. Below the column 4 and preferably also below the bottom 3 is a water sump 5, which is open towards the column 4.

[0022] A fish chamber 12 is thereby created between the bottom 2, wall 3 and column 4.

[0023] At least one circulation pipe 6 is coupled to the sump 5 and extend below the fish tank 1 from the sump 5 to outside the wall 3. The circulation pipe 6 is coupled to a header pipe 7. The header pipe 7 extends vertically along the wall 3 on the outside of the tank 1. From the header pipe a plurality of inlet pipes 8 extend through the wall 3. The inlet pipes 8 are arranged at different levels along the height of the tank. In the embodiment shown in the figure, two circulation pipes 6 and two header pipes 7 are shown. There may also be more than two circulation pipes and header pipes.

[0024] The header pipes 7 extend to a level above the top of the tank 1. At this end the header pipe 7 is open but may be closed by a lid 9. The lid 9 forms a water tight or an airtight closure of the header pipe 7.

[0025] Inside each header pipe 7, at the lower end thereof, is placed a pump 10. The pumps are small recirculation pumps, such as propeller pumps, which have a lifting capacity of about 0,5 metres.

[0026] A wire 11 extends from the top of each header pipe 7, immediately below the lid 9, to the pump 10. The wire 11 is firmly attached to the pump 10. A winch 12 can be attached to the upper end of the wire 11 when the lid 9 is open. The pump 10 is placed at its location in the header pipe 7 so that it can be retrieved by pulling the wire 11. It may be simply placed on a shoulder in the header pipe 7 and maintain its position by its own weight only when not in operation. In operation, the flow will fix the pump to the shoulder.

[0027] The shown placement of the pump 10 at the lower part of the vertical header pipe 7 is ideal for efficient use of the pump. Since the pump only needs provide a small lifting height, equivalent to lifting the water shortly above the water level inside the tank, a pump with a low lifting capacity, such as 0,5 metres can be used.

[0028] The main purpose of being able to retrieve the pump is to be able to maintain the pump, such as retrieving and replacing the pump if necessary. It is also a purpose to facilitate cleaning of the header pipe 7, the inlet pipes 8 and the circulation pipe 6. When the pump 10 has been lifted out of the header pipe 7, the pipes may be flushed by injecting water into the top of the header pipe 7.

[0029] Then the lid 9 is closed and locked to the top of the header pipe 7 to create a water tight or an airtight closure.

[0030] The top of the header pipe may also be lower than the top of the tank 1, and even lower than the water level inside the tank 1, provided the water level inside the tank 1 is lowered when the lid is opened.

[0031] Alternatively, to a lid the header pipe 8 may extend above the maximum lifting height of the pump, so that the water level inside the header pipe is at all times below the top of the header pipe.

[0032] When the pumps 10 are run, water will be drawn from the fish chamber 12 through the screen 13 and into the column 4. The water will flow downwards in the column 4, as shown by the arrows 14, and into the sump 5. From the sump, the water will flow through each of the circulation pipes 6, the pumps 10, the header pipes 7 and through the inlet pipes 8 to the fish chamber 13 again.

[0033] The inlet pipes 8 may be directed at an angle partly along the circumference of the fish tank 1 to set up a revolving current inside the tank 1. The inlet pipes 8 may be connected to nozzles (not shown) inside the fish chamber 13.

[0034] All the water will flow through the recirculation arrangement as explained above. If water treatment external of the fish tank is needed, such as CO2 removal, filtering, heating, cooling etc., this will be handled by a different system than the present invention.

[0035] Despite the above, the water may be oxygenated by supplying oxygen into the water, which is supplied from an oxygen source (not shown). This is possible since such addition of oxygen will not add any resistance to the flow of water. The oxygen may be supplied as pure oxygen, as oxygen enriched air or as air. The oxygen is preferably supplied downstream of the pumps 10, i.e., to the header pipes 8.

Claims (9)

Claims

1. A live fish tank with a dedicated water re-circulation arrangement, comprising a substantially circular fish chamber, having a bottom and a circumferential wall, a vertical column arranged centrally in said fish tank, said column comprising a water permeable partition, a water sump positioned below said column, at least one recirculation pipe coupled to said water sump, said recirculation pipe being coupled to a header pipe extending along the height of said circumferential wall, and a plurality of inlet pipes coupled to said header pipe and extending through said circumferential wall, said inlet pipes being arranged at different levels along said header pipe, wherein a pump is arranged inside said at least one header pipe below the level of a lowermost inlet pipe.

2. The live fish tank with a water circulation arrangement according to claim 1, wherein said header pipe has an open upper end.

3. The live fish tank with a water circulation arrangement according to claim 2, wherein said header pipe extends above the top of the tank.

4. The live fish tank with a water circulation arrangement according to claim 2 or 3, wherein said header pipe comprises a lid at said upper end, said lid selectively making a water tight or airtight closure of said header pipe.

5. The live fish tank with a water circulation arrangement according to claim 2 or 3, wherein said header pipe extends above the level of the maximum lifting height of said pump.

6. The live fish tank with a water circulation arrangement according to any of the preceding claims claim 2 - 5, wherein a wire is attached at a first end to said pump and extends through said header pipe and said wire having a second end approximate the upper end of said header pipe.

7. The live fish tank with a water circulation arrangement according to claim 6, wherein said wire second end has a temporary attachment to the inside of said header pipe immediately below said upper end.

8. The live fish tank with a water circulation arrangement according to claim 6 or 7, wherein said pump is placed on a shoulder inside said header pipe.

9. The live fish tank arrangement of any of the preceding claims, wherein an oxygen source is coupled to said header pipe downstream of said pump.