JPH10248431A - Circulating and filtering device for raising tank for fish kind or the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure of the circulating and filtering device of a raising tank for fish kinds or the like for eliminating a movable part, sufficiently dissolving oxygen in air and simplifying the structure. SOLUTION: Water inside the raising tank 10 mixed with air bubbles is supplied by a circulation pump 13 to a filter 20 for which a biological filtering material is filled inside a casing 21 and is returned to the raising tank by a return pipe 12. For a U-shaped pipe 30 composed of a pair of pipes 30a and 30b whose lower ends are communicated, the upper end part 30c of one pipe is opened inside a downward pocket part P formed at an upper part inside the casing and the upper end part 30d of the other pipe is communicated to the middle of the return pipe. The pocket part P can be omitted. The filter 20 is provided on a position lower than a water surface W inside the raising tank 10 and it is desirable to turn the circulation pump 13 to the one for making the water freely flow from the side of a suction port 13a to the side of an ejection port 13b by the pressure difference in the case that a pressure on the side of the suction port 13a communicated inside the raising tank 10 is higher than the pressure on the side of the ejection port 13b communicated inside the filter 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circulating filtration apparatus for use in breeding tanks for ornamental fish or live corals or invertebrates living in freshwater or seawater.

[0002]

2. Description of the Related Art There are three types of circulating filtration of breeding water for fish and the like of this kind, namely, physical filtration, chemical filtration, and biological filtration, of which biological filtration is particularly important. Biological filtration is based on nitrification by aerobic bacteria and antinitrification by anaerobic bacteria, and it is necessary to maintain a proper balance between these two actions continuously. A wet-dry system in which the biological filtration media is contacted alternately with air and water is well suited for this purpose, examples of which are JP-A-2-2815 or JP-A-2-4414.
There are those disclosed in Japanese Patent Publication No. However, since this uses a mechanical valve mechanism that opens and closes intermittently, there is a possibility that malfunction will occur if wear or scale adheres to the circulating water due to long-term use. However, there is a problem that the dissolution of oxygen is not always sufficient.

On the other hand, the applicant has previously disclosed Patent No. 2038.
No. 421 (Japanese Patent Publication No. 7-73763) was proposed to solve such a problem. This means that the inside of the casing of the filter filled with the biological filtering material is separated into an upper chamber and a lower chamber by a partition wall, and the lower portions of both chambers are communicated with each other by a passage, and one of the U-shaped communication pipes. The upper end is opened in the upper part of the lower chamber, and the other upper end is opened in the upper chamber, and water mixed with water in the breeding tub is supplied to the lower chamber of the filter by a water supply pipe provided with a circulation pump, and is supplied to the lower chamber of the filter. The upper part was connected to the breeding tank by a return pipe.

[0004]

This patent No. 20384 is to be solved.
Although the technique according to No. 21 solves the above-mentioned problems, the structure of the filter is complicated because the inside of the casing is divided into two upper and lower chambers and a passage communicating with each lower part of both chambers is provided. Therefore, there is a problem that the manufacturing cost increases. An object of the present invention is to solve the above-mentioned problems and at the same time to simplify the structure of a filter, and to provide a circulating filtration device for a fish breeding tank that is excellent in function and low in production cost.

[0005]

According to a first aspect of the present invention, there is provided a circulating filter for a breeding tank for fish and the like according to the first invention, which comprises a filter in which a biological filter material is filled in a closed casing and a circulating pump provided on the way. A water supply pipe for supplying the water inside the casing, an air mixing device for mixing air bubbles in the middle of the water supply pipe, and a return pipe for returning the water in the lower part of the casing to the breeding tank. Related to the device,
The discharge port of the return pipe is located at a position higher than the casing, and a pocket portion formed at the upper portion of the casing and closed at the upper side and released at the lower side into the casing, and the lower end thereof communicates with each other and extends upward. One pipe comprises a pair of pipes, and one pipe has a U-shaped pipe whose upper end is opened in the casing inside the pocket part, and the other pipe has an upper end connected to the middle of the return pipe. is there.

[0006] The water in the breeding tub supplied into the casing by the circulation pump is returned to the breeding tub from the outlet of the return pipe, and the water level in the casing gradually decreases due to bubbles supplied together with the water from the water supply pipe. A pressure is applied to the water surface which substantially corresponds to the difference between the water level of one pipe of the U-shaped pipe and the height to the discharge port of the return pipe, which decrease with the water level. When the water level of one of the pipes reaches the lower end of the U-shaped pipe, the air in the casing escapes from the other pipe through the return pipe to the outside, and the water level in the casing rises. If the water level in the return pipe, which reaches or rises with it, reaches the point of communication with the other pipe, this rise stops and falls again as described above. Due to such repeated rise and fall of the water level in the casing, the biological filter material filled in the casing is alternately brought into contact with air and water. The area of contact between water and air in the casing is increased by the adhesion of water to the surface of the biological filter.

In the first invention, it is desirable that the upper end of the other pipe communicated with the return pipe is communicated with the return pipe at a position higher than the opening of the pocket into the casing. . With this configuration, when the air in the casing escapes, the water level in the casing becomes
When it reaches the height of the release part into the casing below the pocket part, the ascent is stopped.

[0008] In a second aspect of the present invention, there is provided a circulating filtration apparatus for a fish breeding tank, wherein a filter in which a biological filter material is filled in a closed casing, and a circulating pump provided in the middle circulates water in the breeding tank. The present invention relates to a circulating filtration device for a breeding tank for fish and the like, comprising a water supply pipe for supplying water into the inside, an air mixing device for mixing air bubbles in the middle of the water supply pipe, and a return pipe for returning water at a lower portion of the casing to the breeding tank. The outlet of the return pipe is located at a position higher than the casing, and a pair of pipes whose lower ends communicate with each other and extend upward therefrom are formed. One pipe has an upper end opened at the upper part in the casing and the other pipe has an upper end. The portion is provided with a U-shaped tube communicated in the middle of the return tube.

In this case, as in the case of the first invention, the water level in the casing gradually decreases due to the bubbles supplied together with the water from the water supply pipe, and the water level of one of the pipes and the water level to the discharge port of the return pipe are increased. A pressure corresponding to the difference is applied. When the water level of one pipe of this U-shaped pipe reaches its lower end, the air in the casing escapes from the other pipe through the return pipe to the outside, and the water level in the casing rises, and this water level falls in the casing. If the water level in the return pipe, which reaches the upper end of one of the open pipes or rises therewith, reaches the communication with the other pipe, this rise stops and drops again as described above. Due to such repeated rise and fall of the water level in the casing, the biological filter material filled in the casing is alternately brought into contact with air and water. The area of contact between water and air in the casing is increased by the adhesion of water to the surface of the biological filter.

[0010] In the second invention, the upper end of the other pipe communicated in the middle of the return pipe is communicated with the middle of the return pipe at a position lower than the upper end of the one pipe opened to the upper part in the casing. Is desirable. With this configuration, when the air in the casing escapes, the water level in the casing stops rising when the water level in the return pipe reaches the height of the upper end of the other pipe.

The casing of each of the above-mentioned inventions is divided into an inlet chamber and a filtration chamber by a partition plate which rises from the bottom plate to a position slightly below the ceiling plate, and the water mixed with air bubbles from the water supply port of the water supply pipe. Is preferably supplied to the inlet chamber, and the return pipe is configured to return the water in the lower portion of the filtration chamber to the rearing tank. By doing so, the portion where the water level rises and falls mainly becomes the portion inside the filtration chamber, and the volume decreases.

[0012] The filter is provided at a position lower than the water surface in the breeding tub, and the circulation pump is configured such that the pressure on the suction port communicating with the breeding tub is higher than the pressure on the discharge port communicating with the filter in the breeding tank. In this case, it is desirable that water flows freely from the suction port side to the discharge port side due to the pressure difference. With this configuration, when the air in the casing passes through the return pipe to the outside, the water in the breeding tank is quickly supplied to the casing through the circulating pump by the siphon action. The water level quickly rises to the above-mentioned rising position.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment shown in FIG. 1 will be described. As shown in FIG. 1, the water supply pipe 11 provided with a circulation pump 13 in the middle thereof has a suction-side tip located in a lower part of a breeding tank 10 for fish, live corals, or invertebrates. A water supply port 11a serving as an outlet end is liquid-tightly inserted and fixed to an upper portion of the inside of the casing 21 of the filter 20. One end of the return pipe 12 has a casing 21.
The discharge port 12 a at the other end is opened near the water surface W of the breeding water in the breeding tub 10. When the circulation pump 13 is operated, the breeding water in the breeding tub 10 is sucked as circulating water from a strainer 14 formed of a plastic basket or the like provided at the suction end of the water supply pipe 11, and supplied to the other end of the water supply pipe 11. The water is supplied from the port 11a to the upper part of the casing 21 of the filter 20. The circulating water supplied into the casing 21 passes through a return pipe 12 from a strainer 15 provided at a lower portion in the casing 21, and from a discharge port 12 a provided at a position higher than the casing 21, to raise the breeding tank 10.
Will be returned within.

The distal end of an air supply pipe 16a of the aeration device 16 is inserted into the water supply pipe 11 at a position slightly lower than the water level W of the breeding water in the breeding tank 10 in a liquid-tight manner.
Due to the negative pressure generated near the insertion portion due to the flow resistance between the strainer 14 and the water supply pipe 11 due to the operation of 3, the outside air is sucked into the water supply pipe 11 as fine bubbles and supplied to the upper part in the casing 21 together with the circulating water. Is done. This intake air amount is controlled by a manual air valve 16 provided at the intake end of the air supply pipe 16a.
It is adjusted by b. The pressure of the suction port 13a communicating with the breeding tank 10 is communicated to the filter 20, such as a centrifugal pump or an electromagnetic pump using a light check valve, in the circulation pump 13 used in this embodiment. When the pressure is higher than the pressure on the discharge port 13b side, water flows freely from the suction port 13a side to the discharge port 13b side due to the pressure difference. The water supply port 11a of the water supply pipe 11 is connected to the casing 21.
May be provided in the lower part of the.

Next, a description will be given of the filter 20 which is an essential part of the present invention. As shown in FIG. 1, the casing 21 of the filter 20 according to the first embodiment has a closed cylindrical shape and is formed of a thick rigid vinyl chloride tube or the like. A downwardly facing cup member 22 whose upper side is closed is fixed by a bracket (not shown) at an upper portion inside the casing 21, and a lower side forms a pocket portion P opened inside the casing 21. A U-shaped pipe 30 composed of a pair of pipes 30a and 30b whose lower ends are communicated with each other and extends upwardly is bent upward at a right angle to one of the pipes 30a and inserted and fixed in the casing 21 in a liquid-tight manner. The upper end portion 30c bent upward again is opened inside the casing 21 inside the pocket portion P. The upper end 30d of the other pipe 30b of the U-shaped pipe 30 is communicated with the return pipe 12 in the middle thereof, and the height of the communicating position is higher than the lower edge of the downward cup member 22 forming the pocket P. .

A filter material exchange port 22 which is closed in a liquid-tight manner by a detachable screw-in lid 23 is provided in a part of an outer wall (a ceiling plate in the illustrated example) of the casing 21. The biological filter material is filled from the exchange port 22, and is exchanged as needed. The biological filtration material is, for example, an air-permeable porous mass of a ceramic material having a size of about 3 cm, and aerobic and anaerobic bacteria are propagated inside the air-permeable pores to perform biological filtration. Is what you do. For example, in the case of the breeding tank 10 of about 150 liters, if the volume of the casing 21 is about 4.5 liters, the water supply amount of the circulation pump 13 is 20 liters per minute, and the air mixing amount is about 0.25 liters per minute. Good.

Next, the operation of the above embodiment will be described.
When the circulation pump 13 is operated, the breeding water in the breeding tub 10 is supplied to the upper part of the casing 21 of the filter 20 via the water supply pipe 11, and the circulating water is supplied from the aeration device 16 as described above. Air is mixed as air bubbles. When the operation is started from an empty state of the casing 21, the breeding water in the breeding tank 10 is mainly sucked into the water supply pipe 11 by the circulation pump 13, and then the water surface W in the breeding tank 10 and the water supply are mainly supplied. Due to the siphon action due to the difference in the height of the water supply port 11a of the pipe 11, the water freely flows through the circulating pump 13 and flows into the casing 21, and the air in the casing 21 passes through the U-shaped pipe 30 and the return pipe 12, and the discharge port 12a. Is discharged from The water level in the casing 21 is downward facing the cup member 22
When the air level rises to the lower edge level L1, the flow of air through the U-tube 30 is cut off, so that the supply of circulating water into the casing 21 by the siphon action is terminated, and the circulating pump 13
The circulating water is supplied by the action of Until then, return pipe 1
2 rises with the water level in the casing 21, but thereafter only the water level in the return pipe 12 rises rapidly and the upper end 30d of the return pipe 30b of the U-shaped pipe 30.
Reaches the level L3 at which the water is communicated, a part of the circulating water flows into the pipe 30b to fill it, the water level in the return pipe 12 continues to rise, and the circulating water flows from the discharge port 12a to the breeding tank. Return to within 10.

Air bubbles mixed into the circulating water supplied from the water supply pipe 11 into the casing 21 are separated and separated from the casing 2.
1, the water level in the casing 21 gradually decreases and immediately falls below the level L1, and the air in the downward cup member 22 communicates with the air in the casing 21. In this state, the height of the water level in the casing-side pipe 30a, which is one of the U-shaped tubes 30, is small if the flow resistance of the biological filter material packed in the casing 21 and the strainer 15 provided thereunder is small. It will be the same as the water level inside. Thereafter, the water level in the casing 21 gradually decreases, and accordingly, the water level in the casing-side pipe 30a of the U-shaped pipe 30 also decreases.
Inside is still full of circulating water. In this state, the air in the casing 21 includes the casing-side pipe 30a.
A pressure corresponding to the difference between the height of the inner water surface and the height of the discharge port 12a of the return pipe 12 is applied.

When the water level in the casing-side pipe 30a drops and reaches the level L2, which is the lower end of the U-shaped pipe 30, the air in the casing 21 flows from the pipe 30a to the pipe 30b.
The air exits from the discharge port 12 a through the return pipe 12, and along with this, air enters the circulating water in the return pipe side pipe 30 b and the rear half of the return pipe 12, and the pressure applied to the air in the casing 21 increases. Since the air drops, the air expands and the circulating water in the latter half of the pipe 30b and the return pipe 12 is discharged at a stretch. For this reason, the pressure in the casing 21 becomes atmospheric pressure, but the breeding water in the breeding tub 10 is mainly circulated by the siphon action due to the difference between the water surface W in the breeding tub 10 and the height of the water supply port 11 a of the water supply pipe 11. Flows freely into the casing 21 so that the casing 21
The air inside is continuously discharged from the discharge port 12a. As a result, the water level in the casing 21 rises, but if the water level rises to the level L1 at the lower edge of the downwardly facing cup member 22, the flow of air through the U-shaped tube 30 is interrupted. The supply of the circulating water to the circulating water ends, and the supply of the circulating water returns to the operation of the circulating pump 13 described above.

Subsequently, as described above, when the water level in the casing 21 and one of the pipes 30a on the side thereof decreases and reaches a level L2, the air in the casing 21 flows from the pipe 30a to the pipe 30b and the return pipe 12. The water is discharged to the outside through the discharge port 12a, and the water level in the casing 21 rises to the level L1. By repeating this action, the water level in the casing 21 becomes the level L1 and the level
The biological filter material filled in the casing 21 is alternately brought into contact with air and water while repeatedly rising and falling during L2.
The period is about 4 minutes in the above numerical example. In a state where circulating water is supplied into the casing 21 by the circulation pump 13 and discharged from the return pipe 12, the casing 21
A water pressure corresponding to the height from the water surface of the casing-side pipe 30a to the discharge port 12a of the return pipe 12 is applied to the air inside.

As described above, according to the first embodiment, since the air and the circulating water are alternately filled in the range of the level L1 and the level L2 in the casing 21, the living organism filled in the range is filled. The media is alternately contacted with air and water to provide a wet-dry system in which aerobic and anaerobic bacteria continue to grow in a balanced manner. This operation is performed by a simple U-shaped tube 30 and does not require any moving parts, so that it can be operated reliably without malfunction for a long period of time, and in addition to the casing 21, a small downward cup member is required. Since only the tube 22 and the U-shaped tube 30 are provided, the structure is extremely simple.

The contact area between the water and the air in the casing 21 increases due to the circulating water adhering to the surface of the biological filtration material. Discharge port 1 of return pipe 12
Since the water pressure corresponding to the height up to 2a is applied, the oxygen is sufficiently dissolved in the circulating water. Thereby, the breeding environment in the breeding tank 10 is greatly improved. Since the casing 21 is hermetically sealed, the filter 20 can
In this case, the pressure applied to the inside of the casing 21 can be further increased, and the dissolution of oxygen in the circulating water can be further increased.

In the above description of the operation, the flow resistance of the strainer 15 has been described as being small. However, when the strainer having a high flow resistance is used or the flow resistance of the strainer is increased due to clogging, the pressure loss due to the increase of the flow resistance is reduced. The water level in the casing-side pipe 30a is lower than the water level in the casing 21 by that amount. Therefore, the casing 21
Before the water level in the inside reaches the level L2, the water level in the pipe 30b reaches the level L2, air is released, and the water level in the casing 21 rises. Somewhat smaller. While the air in the casing 21 is evacuated, the water level in the return pipe 12 rises slightly later than the water level in the casing 21 due to the flow resistance.

The level L3 of the upper end 30d of the return pipe 30b communicated with the return pipe 12 is lower than the level L1 of the lower edge of the downward cup member 22, so that the casing 21
If the water level in the return pipe 12 reaches the level L3 before the water level in the pipe reaches the level L1, the return pipe 30b at that time
Since the circulating water flows into the inside and the flow of the air passing through the U-shaped tube 30 is cut off, the supply of the circulating water from the breeding tub 10 to the casing 21 by the siphon action ends. Therefore, in this case, the air and the circulating water are alternately filled in the range of the level L2 and the level L3 in the casing 21.

The pocket P whose lower side is released into the casing 21 hangs from the ceiling plate of the casing 21 as shown in FIG. 2, instead of being formed by the downwardly facing cup member 25 as in the above-described embodiment. 3, a box member 27 is fixed to one side of the upper part of the casing 21 in a liquid-tight manner, and the lower part is formed by an opening 27a. It may be formed by releasing it into the inside 21. Alternatively, as shown in FIG. 4, the pocket portion P may be formed by a cylindrical extension portion 28 provided integrally below the screwed lid 23. Further, in the modification shown in FIG. 4, the U-shaped tube 30 is provided in the casing 21, but the U-shaped tube 30 can be provided in the casing 21 also with the one shown in FIGS. Although not shown in FIG. 2 to FIG. 4, air bubbles are mixed in the circulating water
The structure of the portion for supplying 0 is the same as that of FIG.

Next, a second embodiment shown in FIG. 5 will be described. In this embodiment, the upper end portion 30d of the return pipe 30b having no pocket portion P and communicating with the return pipe 12 is provided.
Level L3 is the upper end 30c of the casing side pipe 30a.
Is different from the first embodiment only in that the level is lower than the level L1 of the first embodiment, and the other structures are the same.

If the circulating pump 13 is operated while the casing 21 is empty, the breeding water in the breeding tub 10 flows into the casing 21 by siphon action as in the case of the first embodiment, The air in 21 is discharged from the discharge port 12a through the U-shaped pipe 30 and the return pipe 12. Return pipe 1 rising with water level in casing 21
When the water level in 2 rises to the level L3 at which the upper end 30d of the return pipe 30b of the U-shaped pipe 30 is connected, the circulating water flows into the pipe 30b and the flow of air through the U-shaped pipe 30 is cut off. Therefore, the supply of the circulating water into the casing 21 by the siphon action ends, and the supply of the circulating water by the action of the circulating pump 13 is achieved. After that, return pipe 12
Only the inside water level rises rapidly, and the circulating water returns to the breeding tank 10 from the discharge port 12a.

Air bubbles mixed into the circulating water supplied from the water supply pipe 11 into the casing 21 are separated and
1, the water level in the casing 21 gradually decreases, and the water level in the casing-side pipe 30 a also decreases with the water level in the casing 21. In this state, as in the first embodiment, the air in the casing 21 is filled with the water surface in the casing-side pipe 30a and the discharge port 1 of the return pipe 12.
Pressure corresponding to the height difference of 2a is applied.

When the water level in the casing side pipe 30a, which decreases with the water level in the casing 21, reaches the level L2, the air in the casing 21 is discharged as described above.
Then, the water is discharged from the discharge port 12a to the outside through the return pipe 12, and the water level in the casing 21 rises to the level L3. By repeating this operation, the casing 21
The water level in the inside repeatedly rises and falls between the level L2 and the level L3, and the biological filter material filled in the casing 21 is alternately contacted with air and water.

In the second embodiment, as in the first embodiment, the casing 21 is alternately filled with air and circulating water in the range between the level L2 and the level L3.
Biological media loaded in that area are alternately contacted with air and water to provide a wet-dry system in which aerobic and anaerobic bacteria continue to grow in a balanced manner.
And this action is better done by a simple U-tube 30,
Since there is no need for any movable parts, it operates reliably without malfunction for a long period of time, and in addition to the casing 21, only the U-shaped tube 30 is required to form the pocket portion P, such as a downwardly facing cup member 22. Is also unnecessary, so that the structure is simpler. Also in this case, the casing 21
The contact area between the water and the air in the inside increases due to the circulating water adhering to the surface of the biological filtration material, and furthermore, the casing 2
The air in 1 is subjected to a water pressure corresponding to the height from the water surface of the casing side pipe 30a to the discharge port 12a of the return pipe 12, so that oxygen is sufficiently dissolved in the circulating water, and this pressure is It can be further increased by placing the filter 20 considerably below the breeding tank 10.

If the level L1 is made higher than the level L3 in the second embodiment, the level
Air and circulating water are alternately filled in the range of L1 and level L2.

Next, a third embodiment shown in FIG. 6 will be described. In this embodiment, the inside of the casing 21 is liquid-tightly separated into an inlet chamber R1 and a filtration chamber R2 by a partition plate 29 which rises from a bottom plate of the casing 21 to a position immediately below the ceiling plate. Is inserted and fixed to the lower part of the inlet chamber R1 in a liquid-tight manner, one end of the return pipe 12 is inserted and fixed to the lower part of the filtration chamber R2, and the biological filtration material is filled only in the filtration chamber R2. It is different from the form. The upper edge of the partition plate 29 is the upper end 30c of the casing-side pipe 30a.
May be higher or lower than the level L1 of the communication position of R1, and both portions R1 and R2 are connected at a portion above the upper edge.

If the circulating pump 13 is operated while the casing 21 is empty, the breeding water in the breeding tub 10 first flows into the inlet chamber R1 by the above-mentioned siphon action, and then the upper edge of the partition plate 29 is removed. And flows into the filtration chamber R2,
The air in the casing 21 is discharged from the discharge port 12a through the U-shaped pipe 30 and the return pipe 12. The water level in the return pipe 12, which rises with the water level in the filtration chamber R2, exceeds the height of the upper edge of the partition plate 29 and rises to the level L3 to which the upper end 30d of the return pipe 30b of the U-shaped pipe 30 is connected. Then, as described above, the flow of the air passing through the U-shaped pipe 30 is cut off, so that the supply of the circulating water into the casing 21 by the siphon action ends, and the supply of the circulating water by the action of the circulating pump 13 is performed. . In this case, the water level mainly in the filtration chamber R2 (the part above the upper edge of the partition plate 29 in the filtration chamber R2 and the casing 21) gradually decreases due to bubbles mixed in the circulating water, and the casing-side pipe 30a The height of the water level in the casing 21 also decreases with the water level in the casing 21, but the water level in the inlet chamber R 1 does not drop below the upper edge of the partition plate 29. In this state, the air in the casing 21 includes the water surface in the casing-side pipe 30a and the discharge port 1 of the return pipe 12.
Pressure corresponding to the height difference of 2a is applied.

When the water level in the casing-side pipe 30a, which decreases with the water level in the casing 21, reaches the level L2, the air in the casing 21 is discharged from the pipe 30a through the pipe 30b and the return pipe 12 to the outside through the discharge port 12a. Then, the water level mainly in the filtration chamber R2 rises to the position of the level L3. By repeating this action, mainly the water level in the filtration chamber R2 repeatedly rises and falls between the level L2 and the level L3, and the biological filter material filled in the filtration chamber R2 alternates between air and water. Contacted.

In the third embodiment, as in the second embodiment, a wet-dry system in which the biological filtration material is alternately contacted with air and water is obtained, and the movable part is formed. Since no operation is required, the operation can be performed reliably without malfunction for a long period of time, and further, the structure is simpler, and each effect that oxygen is sufficiently dissolved in the circulating water can be obtained. Moreover, in this embodiment, the portion where the water level repeatedly rises and falls is mainly only in the filtration chamber R2 and the volume is reduced, so that the number of repetitions per unit time is increased and the display effect is enhanced. Note that this effect is also obtained in the casing 21 in the first and second embodiments.
Can also be obtained by reducing the volume of

This third embodiment can be applied not only to the second embodiment as shown in FIG. 6, but also to the first embodiment. The position of the upper edge of the partition plate 29 may be lower than the height of the level L1.
In that case, the water level rises and falls only in the filtration chamber R2. Further, the partition plate 29 is not limited to the flat plate as shown in FIG. 6, but may be a cylindrical one rising from the bottom plate of the casing 21 to partition the inside of the casing 21 into an inlet chamber R1 and a filtration chamber R2. The plate can be easily fixed.

In the above embodiments, when the pressure on the suction port 13a side is higher than the pressure on the discharge port 13b, the circulating pump 13 causes water to flow from the suction port 13a side to the discharge port 13b side due to the pressure difference. Is used, but a positive displacement type that does not have such an effect can be used. In that case, when the air in the casing 21 passes through the U-shaped pipe 30 and the return pipe 12,
The siphon action does not work due to the difference between the water surface W in the inside and the height of the water supply port 11a of the water supply pipe 11, but the water surface in the casing 21 is caused by the circulating water supplied into the casing 21 by the circulation pump 13 as described above. And then the circulating water passes through the return pipe 12 to the discharge port 12a.
From the breeding tank 10.

It is to be noted that the air mixing device 16 may be configured such that air is introduced into the water supply pipe 11 by an air pump instead of the device that sucks air by negative pressure as in the illustrated embodiment.

[0039]

As described above, according to the first aspect, the biological filter material filled in the casing is alternately contacted with air and water by repeatedly raising and lowering the water level in the casing. Thus, a wet-dry system is obtained in which the biological filter is contacted alternately with air and water, which greatly improves the rearing environment in the tank. In addition to the increase in the contact area between the water and air in the casing, the surface of the water in the casing is subjected to a pressure almost equivalent to the difference from the height to the outlet of the return pipe. Dissolution also increases. And the action of this water level repeatedly rising and falling is a simple U which connects the lower ends of a pair of pipes.
It is performed more reliably by means of a pipe and does not require any moving parts, so that it operates reliably for a long time without malfunction. Moreover, the inside of the casing is separated into upper and lower chambers,
Since there is no need to provide such a passage connecting the lower portions of the two chambers, it is possible to simplify the structure of the filter and reduce the production cost of the circulating filtration device for a fish breeding tank.

According to the second aspect, in addition to the same effects as those of the first aspect, since a pocket is not required, the structure can be simplified by that much and the manufacturing cost can be reduced.

The casing of each invention is separated into an inlet chamber and a filter chamber by a partition plate, water containing air bubbles from the water supply port of the water supply pipe is supplied to the inlet chamber, and a return pipe is provided at the lower part of the filter chamber. If the water is returned to the breeding tub, the volume of the part where the water level rises and falls will decrease, so the number of repetitions per unit time will increase, and the change in the circulation state in the breeding tub will increase, and the display effect will increase. Increase.

The filter is provided at a position lower than the water level in the breeding tank, and the circulating pump is configured such that the pressure at the suction port connected to the breeding tank is higher than the pressure at the discharge port connected to the filter. In this case, if the pressure difference allows water to freely flow from the suction port side to the discharge port side, the return speed of the water level in the casing increases, and the volume of the portion where the water level rises and falls does not need to be reduced. As the number of times the biological filtration material is alternately contacted with air and water is increased, not only the display effect is enhanced, but also the performance of the biological filtration is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall structure of a first embodiment of a circulating filtration device for a fish breeding tank according to the present invention.

FIG. 2 is a diagram showing a modification of the filter according to the first embodiment.

FIG. 3 is a diagram showing a different modification of the filter of the first embodiment.

FIG. 4 is a diagram showing still another modification of the filter of the first embodiment.

FIG. 5 is a diagram showing the overall structure of a second embodiment of the circulating filtration device for a fish breeding tank according to the present invention.

FIG. 6 is a view showing a structure of a filter 20 of a third embodiment of a circulating filtration device for a fish breeding tank according to the present invention.

[Explanation of symbols]

10 ... breeding tank, 11 ... water supply pipe, 12 ... return pipe, 12a ...
Discharge port, 13: circulation pump, 16: air mixing device, 20
... Filter, 21 ... Casing, 29 ... Partition plate, 30 ... U
Pipe, 30a ... pipe (casing side pipe), 30b
... pipe (return pipe side pipe), 30c, 30d ... upper end, P ... pocket, R1 ... inlet chamber, R2 ... filtration chamber, W
... water surface.

Claims (6)

[Claims] 1. A filter in which a biological filtration material is filled in a closed casing, a water supply pipe for supplying water in a breeding tank to the casing by a circulation pump provided in the middle, and a water supply pipe in the middle of the water supply pipe. In a circulating filtration device for a fish breeding tub comprising a return pipe for returning water in the lower part of the casing to the breeding tub, a discharge port of the return pipe is positioned higher than the casing. A pocket portion formed at an upper part in the casing and closed at an upper part and opened at a lower part in the casing, and a pair of pipes whose lower ends communicate with each other and extend upward, and one of the pipes is A fish or the like breeder characterized in that an upper end portion is opened in the casing inside the pocket portion, and the other pipe has a U-shaped tube whose upper end portion is communicated in the middle of the return pipe. Circulation filtration device for growing tank. 2. The return pipe according to claim 2, wherein an upper end of the other pipe communicated with the return pipe is communicated with the return pipe at a position higher than a release portion of the pocket into the casing. Item 2. A circulating filtration device for a fish breeding tank according to Item 1. 3. A filter in which a biological filter material is filled in a closed casing, a water supply pipe for supplying water in the breeding tank into the casing by a circulation pump provided in the middle, and a middle part of the water supply pipe. In a circulating filtration device for a fish breeding tub comprising a return pipe for returning water in the lower part of the casing to the breeding tub, a discharge port of the return pipe is positioned higher than the casing. A pair of pipes whose lower ends are communicated with each other and extend upward, one of the pipes has an upper end opened at the upper part in the casing, and the other pipe has an upper end communicated with the return pipe halfway. A circulating filtration device for a fish breeding tank, comprising a U-shaped tube. 4. An upper end of the other pipe communicated in the middle of the return pipe is communicated with a middle of the return pipe at a position lower than an upper end of one of the pipes opened to the upper part in the casing. The circulating filtration device for a fish breeding tank according to claim 3, wherein the circulating filtration device is used. 5. The interior of the casing is separated into an inlet chamber and a filtration chamber by a partition plate rising from the bottom plate of the casing to a position slightly below the ceiling plate, and air bubbles from the water supply port of the water supply pipe are mixed therein. The fish or the like according to any one of claims 1 to 4, wherein the water is supplied into the inlet chamber, and the return pipe is configured to return water in a lower portion of the filtration chamber into the rearing tank. A circulating filtration device for breeding tanks. 6. The filter is provided at a position lower than the surface of the water in the breeding tub, and the circulation pump is provided on a discharge port side in which a pressure on a suction port communicating with the breeding tub is communicated with the filter. When the pressure is higher than the pressure, water flows freely from the suction port side to the discharge port side due to the pressure difference. The circulation of the fish breeding tank according to any one of claims 1 to 5, Filtration device.