# Patent

## Title
Aquaculture pump system and method

## Abstract

Embodiments of the invention provide a method of operating a pump in an aquaculture system including a water tank that houses aquatic life. The method includes monitoring a dissolved oxygen level in the culture tank, determining a flow rate threshold based on the dissolved oxygen level, and changing a speed of the pump to maintain a current flow rate through the culture tank above the flow rate threshold.

## Background
RELATED APPLICATIONS
This application claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 61/568,427 filed on Dec. 8, 2011, the entire contents of which is incorporated herein by reference.


BACKGROUND
Pumps can be used to recirculate water in aquatic farms, such as recirculating aquaculture systems in which fish and other aquatic life are raised. Recirculating aquaculture systems generally include one or more tanks to house the fish, one or more water inlets into the tank, and one or more water outlets out of the tank. The water outlets are connected to an inlet of the pump. The pump generally propels the water through a filter and back into the tank through the water inlets.
Conventional recirculating aquaculture systems have a sizable upfront cost to design and build, and also have high operating costs that make it difficult for recirculating aquaculture farmers to compete with other types of aquaculture farms, such as ponds and net pen operations. Conventional recirculating aquaculture systems usually provide manually adjusted oxygen flow into the tank and manually adjusted water flow through the culture tank depending upon the size or requirements of the aquatic life. As a result, typical recirculating aquaculture farms spend anywhere from $100,000.00 to $1,000,000.00 in electrical cost and $1,700 to $4,000 in oxygen costs on an annual basis. In fact, the highest operating costs for recirculating aquaculture farms are feed, electricity, and oxygen.
In conventional recirculating aquaculture systems, there are several parameters that must be frequently monitored by the farmers in order to determine when feed rates for the fish may be increased. Presently, aquaculture farmers must monitor fecal output of the fish daily. Every 30 minutes to 2 hours, they must monitor the amount of feed the fish can be induced to consume. In addition, they must monitor the oxygen consumption of the fish and the culture system water constantly. Therefore, a need exists for a way in which to lower the production cost and operating cost of recirculating aquaculture systems.
SUMMARY
Some embodiments of the invention provide a method of operating a pump in an aquaculture system including a culture tank that houses fish. The method can include monitoring a dissolved oxygen level in the culture tank, determining a flow rate threshold based on the dissolved oxygen level, and changing a speed of the pump to maintain a current flow rate through the culture tank above the flow rate threshold.
Some embodiments of the invention provide a recirculating aquaculture system including a culture tank, a sensor, a variable speed pump, and a controller. The sensor is configured to measure a dissolved oxygen level in the culture tank. The variable speed pump is configured to circulate water through the culture tank. The controller is in communication with the sensor and the variable speed pump, and is configured to determine an oxygen threshold, compare the oxygen threshold with the dissolved oxygen level measured by the sensor, and increase a speed of the variable speed pump to adjust a flow rate through the culture tank when the oxygen threshold is below the dissolved oxygen level measured by the sensor.



DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an aquaculture system according to one embodiment of the invention.
FIG. 2 is a perspective view of a pump for use in the system of FIG. 1.
FIG. 3 is an exploded perspective view of the pump of FIG. 2.
FIG. 4 is a front view of an on-board controller for use with the pump of FIGS. 2 and 3.
FIG. 5 is a perspective view of an external controller for use with the system of FIG. 1.



DETAILED DESCRIPTION
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives and fall within the scope of embodiments of the invention.
FIG. 1 illustrates an aquaculture system 10 according to one embodiment of the invention. The aquaculture system 10 can include one or more variable speed pumps 12 in communication with one or more controllers 14, such as one or more variable frequency drives (VFD). If more than a single pump 12 is used, the pumps 12 can be controlled in a cascading manner. The aquaculture system 10 can include a biofilter 16 and sensors measuring one or more of the following: ammonia, nitrite, nitrate, and solids removal. The aquaculture system 10 can include one or more water tanks, or culture tanks, 20 housing the fish. The aquaculture system 10 can include a dissolved oxygen sensor 22 coupled to the culture tank 20. The aquaculture system can include a positional, remote-controlled, oxygen solenoid valve 24 coupled to the culture tank 20. The oxygen solenoid valve 24 can be coupled to an oxygen cone 26, which can be coupled to an oxygen tank 28.
The pump 12 can be a variable speed pump operated according to a flow control algorithm, as disclosed in U.S. Pat. No. 7,845,913 entitled “Flow Control” and issued Dec. 7, 2010, the entire contents of which is herein incorporated by reference. The controller 14 can read water quality information including dissolved oxygen, as well as other water quality variables. The controller 14 can be a separate component from the pump 12 or can be integrated into the variable speed pump 12.
The controller 14 can be connected to the various sensors, including the dissolved oxygen sensor 22, as well as the solenoid valve 24 in control of the oxygen supply. In some embodiments, the controller 14 can be in two-way communication with the biofilter 16, the dissolved oxygen sensor 22, and the solenoid valve 24. Two-way communication in the aquaculture system 10 can be performed as disclosed in U.S. Pat. No. 7,854,597 entitled “Pumping System with Two-Way Communication” and issued on Dec. 21, 2010, the entire contents of which is herein incorporated by reference.
The controller 14 can operate the pump 12 to control water flow and the solenoid valve 24 to control oxygen delivery based on the principles of fish growth. When fish are fingerlings, they require X amount of oxygen and Y amount of water flow to have the continuous and substantial growth that is required in aquaculture systems. As the fingerlings mature into market-size fish, the formulas change to the following:

X+Ratio of Respiration Required by Larger Fish (in ppm of oxygen)=New Oxygen Requirement/Time; and

Y+Flow Required by Maturing Fish for Water Quality and Safe Swimming Velocity=Clean Water Standard of X Ammonia/PH/Solids Removed, etc.

The new oxygen requirement/time can also incorporate the oxygen demand of the water with increased nutrient loading.
Presently, aquaculture farmers must monitor fecal output of the fish daily. Every 30 minutes to 2 hours, the farmers must monitor the amount of feed the fish can be induced to consume. In addition, the farmers must monitor oxygen consumption of the fish constantly. The aquaculture system 10 according to some embodiments of the invention allows the farmer to measure a single parameter (i.e., dissolved oxygen) that summarizes all conditions for continued feeding. In some embodiments, the aquaculture system 10 can be used to tell the farmer where and when to feed.
As the fish grow, their oxygen and water flow requirements change. As a result, the electrical and oxygen costs of an aquaculture farm change with the life cycle or respiration potential of a fish through its growth cycle. In other words, the electrical and oxygen costs of an aquaculture farm change with the dissolved oxygen requirements and water treatment needs of the fish as they grow. In conventional recirculating aquaculture systems, an operator must manually adjust oxygen flow and/or water flow (i.e., through manual valves to adjust flow paths) periodically to meet oxygen and water flow requirements.
The aquaculture system 10 according to embodiments of the invention can be used with any scale of culture tank(s) 20 through any part of the lifecycle of aquatic life requiring oxygen. The aquaculture system 10 can operate to keep dissolved oxygen substantially constant by varying the flow of water, coupled with the flow of oxygen, by monitoring and pinpointing respiration and circulation requirements. In other words, the controller 14 can monitor a dissolved oxygen level in the culture tank 20 and can increase oxygen flow into the culture tank 20 if the dissolved oxygen level is below an oxygen threshold. The controller 14 can also, or alternatively, determine a flow rate threshold based on the dissolved oxygen level, and increase water flow through the culture tank 20 by adjusting a speed of the pump 12 (e.g., by providing an updated speed control command to the pump 12) if the dissolved oxygen level is below the flow rate threshold. Accordingly, the dissolved oxygen level in the culture tank 20 can be increased by changing the speed of the pump 12 and increasing the flow rate of water through the culture tank 20.
In some embodiments, the controller 14 can incrementally increase the speed of the pump 12 until dissolved oxygen levels are at or above the oxygen threshold. In other words, the controller 14 can determine the oxygen threshold (e.g., based on respiration requirements of the aquatic life in the culture tank 20, as discussed above), compare the oxygen threshold to the measure dissolved oxygen level, and increase the speed of the pump 12 and, thus, the flow rate through the culture tank 20 when the measure dissolved oxygen level is below the oxygen threshold. The controller 14 can continuously monitor the dissolved oxygen level and increase the speed of the pump 12 until a flow rate through the culture tank 20 that maintains the dissolved oxygen level at or above the oxygen threshold is reached. In some embodiments, an operator can also manually adjust the speed of the pump 14 through a user interface of the controller 14, as further discussed below.
The aquaculture system 10 can cadence off of the requirements for the fish and only require full normal operation of the pump 12 toward the end of the aquatic life growth curve. This would potentially save the farmer 50 percent to 70 percent of the normal operating costs associated with water flow and oxygen delivery (e.g., electrical and oxygen costs).
FIG. 2 illustrates an embodiment of the pump 12 for use with the aquaculture system 10. The pump 12 can include a housing 112, a motor 114, and an on-board controller 116 (which can include the variable frequency drive controller 14). In some embodiments, the motor 114 can be a variable speed motor. In one embodiment, the motor 114 can be driven at four or more different speeds. The housing 112 can include an inlet 118, an outlet 120, a basket 122, a lid 124, and a stand 126. The stand 126 can support the motor 114 and can be used to mount the pump 12 on a suitable surface (not shown).
In some embodiments, the on-board controller 116 can be enclosed in a case 128. The case 128 can include a field wiring compartment 130 and a cover 132. The cover 132 can be opened and closed to allow access to the on-board controller 116 and protect it from moisture, dust, and other environmental influences. The case 128 can be mounted on the motor 114. In some embodiments, the field wiring compartment 130 can include a power supply to provide power to the motor 114 and the on-board controller 116.
FIG. 3 illustrates the internal components of the pump 12 according to one embodiment of the invention. The pump 12 can include a seal plate 134, an impeller 136, a gasket 138, a diffuser 140, and a strainer 142. The strainer 142 can be inserted into the basket 122 and can be secured by the lid 124. In some embodiments, the lid 124 can include a cap 144, an O-ring 146, and a nut 148. The cap 144 and the O-ring 146 can be coupled to the basket 122 by screwing the nut 148 onto the basket 122. The O-ring 146 can seal the connection between the basket 122 and the lid 124. An inlet 152 of the diffuser 140 can be fluidly sealed to the basket 122 with a seal 150. In some embodiments, the diffuser 140 can enclose the impeller 136. An outlet 154 of the diffuser 140 can be fluidly sealed to the seal plate 134. The seal plate 134 can be sealed to the housing 112 with the gasket 138. The motor 114 can include a shaft 156, which can be coupled to the impeller 136. The motor 114 can rotate the impeller 136, drawing fluid from the inlet 118 through the strainer 142 and the diffuser 140 to the outlet 120.
In some embodiments, the motor 114 can include a coupling 158 to connect to the on-board controller 116. In some embodiments, the on-board controller 116 can automatically operate the pump 12 according to at least one schedule. In some embodiments, the on-board controller 116 can allow a manual operation of the pump 12. In some embodiments, the on-board controller 116 can monitor the operation of the pump 12 and can indicate abnormal conditions of the pump 12.
FIG. 4 illustrates a user interface 160 for the on-board controller 116 according to one embodiment of the invention. The user interface 160 can include a display 162, at least one speed button 164, navigation buttons 166, a start-stop button 168, a reset button 170, a manual override button 172, and a “quick clean” button 174. The manual override button 172 can also be called “time out” button. In some embodiments, the navigation buttons 166 can include a menu button 176, a select button 178, an escape button 180, an up-arrow button 182, a down-arrow button 184, a left-arrow button 186, a right-arrow button 188, and an enter button 190. The navigation buttons 166 and the speed buttons 164 can be used to program a schedule into the on-board controller 116. In some embodiments, the display 162 can include a lower section 192 to display information about a parameter and an upper section 194 to display a value associated with that parameter. In some embodiments, the user interface 160 can include light emitting diodes (LEDs) 196 to indicate normal operation and/or a detected error of the pump 12.
FIG. 5 illustrates an external controller 198 for the pump 12 according to one embodiment of the invention. The external controller 198 can communicate with the on-board controller 116. The external controller 198 can control the pump 12 in substantially the same way as the on-board controller 116. The external controller 198 can be used to operate the pump 12 and/or program the on-board controller 116, if the pump 12 is installed in a location where the user interface 160 is not conveniently accessible.
It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein. Various features and advantages of the invention are set forth in the following claims.

## Claims

1. A method of operating a pump in an aquaculture system, the aquaculture system including a culture tank that houses aquatic life, a sensor, an oxygen cone in direct fluid communication with the culture tank through an oxygen solenoid valve, a biofilter in fluid communication with the culture tank and the pump, and a programmable controller in communication with the sensor, the oxygen solenoid, and the pump, the method comprising:
recirculating water through the culture tank at a flow rate;
recirculating the water through the biofilter;
measuring a dissolved oxygen level in the culture tank with the sensor;
setting a flow rate threshold with the programmable controller based on the dissolved oxygen level and oxygen requirements of the aquatic life in the culture tank;
retrieving a current dissolved oxygen level measured by the sensor;
comparing the flow rate threshold with the current dissolved oxygen level measured by the sensor; and
when the current dissolved oxygen level is below the flow rate threshold, the programmable controller increasing a speed of the pump to increase the flow rate through the culture tank and operating the oxygen solenoid valve to control an oxygen flow into the culture tank until the dissolved oxygen concentration is greater than or equal to the set flow rate threshold.

2. The method of claim 1 and further comprising monitoring at least one of ammonia, nitrite, nitrate, and solids removal.

3. The method of claim 2 and further comprising monitoring using sensors in the biofilter.

4. The method of claim 1 and further comprising increasing oxygen flow into the culture tank if the dissolved oxygen level is below an oxygen threshold and remotely operating the solenoid valve in order to increase oxygen flow.

5. The method of claim 4 and further comprising providing two-way communication between the pump and the solenoid valve.

6. The method of claim 1 and further comprising using a flow control algorithm to operate the pump to maintain the flow rate.

7. The method of claim 1 wherein the flow rate threshold is a requirement for water quality and safe swimming velocity of the fish.

8. The method of claim 1 and further comprising determining when to feed the fish based on the dissolved oxygen level.

9. A recirculating aquaculture system for aquatic life, the system comprising:
a culture tank configured to hold aquatic life therein;
an oxygen cone in direct fluid communication with the culture tank through an oxygen solenoid valve;
a sensor configured to measure a dissolved oxygen level in the culture tank;
a variable speed pump configured to circulate water through the culture tank at a flow rate;
a biofilter in fluid communication with the culture tank and the variable speed pump; and
a programmable controller in communication with the sensor, the oxygen solenoid valve, and the variable speed pump, wherein the programmable controller is configured to:
set a dissolved oxygen threshold for the culture tank based on an oxygen requirement of the aquatic life therein,
retrieve a current dissolved oxygen level measured by the sensor,
compare the dissolved oxygen threshold with the current dissolved oxygen level measured by the sensor, and
when the current dissolved oxygen level is below the dissolved oxygen threshold,
increasing the flow rate within the culture tank by increasing a speed of the variable speed pump and operating the oxygen solenoid valve to control an oxygen flow into the culture tank until the current dissolved oxygen level measured by the sensor is greater than or equal to the set dissolved oxygen threshold.

10. The recirculating aquaculture system of claim 9, wherein the controller includes a variable frequency drive.

11. The recirculating aquaculture system of claim 9, wherein the controller is configured to determine a flow rate threshold based on the dissolved oxygen level and increase the speed of the variable speed pump to adjust the flow rate through the culture tank above the flow rate threshold.

12. The recirculating aquaculture system of claim 9, wherein the controller is configured to update the dissolved oxygen threshold based on a respiration requirement of aquatic life in the culture tank.

13. The recirculating aquaculture system of claim 9, wherein the controller includes a user interface, and the controller is configured to change the speed of the variable speed pump based on user input from the user interface.

14. The recirculating aquaculture system of claim 9, wherein the controller is integrated into the variable speed pump.

15. The recirculating aquaculture system of claim 9, wherein the controller is configured to determine at least one condition for feeding aquatic life in the culture tank from the dissolved oxygen level measured by the sensor.

16. The recirculating aquaculture system of claim 9, wherein the controller is an on-board controller adjacent to the pump.