Aquaculture Water Systems and Management

A set of vocabulary flashcards based on aquaculture water systems and management concepts, encompassing various aspects of water source selection, environmental controls, system functionality, and measurements.

Water source selection

Important in aquaculture as it affects temperature, oxygen levels, water quality, and disease risk critical for fish health and growth.

Well water advantages

Consistent temperature, dissolved oxygen, and pathogen-free.

Disadvantages of well water

Expensive, hard to repair, and can become supersaturated with gases.

Degassers

Required for wells to remove nitrogen gas that causes gas bubble disease.

Surface water variability

Affected by seasonal changes like temperature, dissolved oxygen, and flow.

Main risk of surface water

Pollution from upstream and fish pathogens from wild populations.

Municipal water in hatcheries

Not used because it’s expensive and contains chlorine and fluoride which kill fish.

Safe use of domestic water

Can be used in recirculation systems after off-gassing.

Cage culture systems downside

No control over water quality including temperature, dissolved oxygen, plankton, and turnover.

Aquaculture system filters

Remove solids, bacteria, and waste from incoming or recirculated water.

Types of filters

Includes rotary drum, sand, and fluidized bed filters.

Rotary drum filters

Automatic, but more expensive to install and maintain.

Degasser function

Prevents gas supersaturation that causes bubble disease.

Nitrogen supersaturation risk

Occurs when nitrogen exceeds 104% saturation.

Types of degassers

Vacuum and packed column.

Common type of degasser

Packed column degasser.

UV system function

Disinfects water by killing pathogens with ultraviolet light.

Factors affecting UV dose effectiveness

Flow rate, turbidity, and bulb age.

Bulbs in effluent UV system

Contains 6 bulbs.

Ozone in water treatment

A powerful disinfectant and backup to UV.

Three main oxygen sources

Compressed cylinders, liquid oxygen, and on-site generators.

Mazzei injector purpose

Injects oxygen into water by mixing air and water under pressure.

Heat exchanger function

Transfers heat from boiler water to hatchery process water.

Air compressors supply

Air for valves, oxygen generators, and degassing systems.

Backup generator maintenance

Test monthly, service every 6 months, load test yearly.

Sea cage automation examples

Includes feeding, grading, and fish counting.

Land-based hatchery automation

Includes flow control, pump speed, feeding, oxygen, and temperature.

Variable Frequency Drive (VFD) function

Adjusts pump speed and prevents deadheading.

Flow measurement types

Includes paddle wheel, ultrasonic, and magnetic.

Most accurate flow meter

Ultrasonic flow meter.

Cheaper but intrusive flow meter

Paddle wheel flow meter.

Types of dissolved oxygen sensors

Optical and membrane sensors.

Optical DO sensor pros and cons

Accurate and low maintenance, but expensive.

Membrane DO sensor pros and cons

Accurate and cheaper, but needs membrane replacement and water flow.

Temperature automation tools

Uses temperature probes and 3-way valves.

What is a PLC?

Programmable Logic Controller that reads sensors and controls pumps and valves.

What is a BCS/BMS/BAS system?

Building Control System that monitors alarms, chillers, and oxygen systems.

PLC vs BCS difference

PLC = hardware (controls), BCS = software (monitors).

Types of rearing units

Includes heath trays, upwelling jars, cages, ponds, raceways, and circular tanks.

Factors determining rearing units

Location, cost, fish species, and operator preference.

Volume of a cube formula

Length × Width × Height.

Volume of a cylinder formula

3.14 × (radius²) × height.

Importance of tank volume

To calculate fish density and water exchange rate.

Water flow in heath trays

Enters back → up through tray → exits front → cascades to next.

Function of an upwelling jar

Water flows up through eggs, removing dead eggs at the top.

Management difficulty of upwelling jars

Dead eggs are hard to remove and can cause fungus.

Raceway flow type

Plug flow — water flows in one end and out the other.

Fish density in conservation raceways

20–40 g/L (1 exchange per hour).

Fish density in commercial raceways

40–70 g/L (2–4 exchanges per hour).

Raceway standpipe functions

Short = clean surface water; tall = solids/waste removal.

Drawbacks of raceways

Uneven flow and solids settle downstream.

Conversion of 1 g/L to kg/m³

1 g/L = 1 kg/m³.

Water flow in circular tanks

Tangentially to create rotational and radial 'tea cup' flow.

Ideal water velocity in circular tanks

0.5–2 body lengths per second.

Self-cleaning feature of circular tanks

Rotational flow moves solids to the center drain.

Types of flow in circular tanks

Primary rotating flow and secondary radial flow.

Swede tanks

Square-circle hybrid tanks, known for poor corner flow, used for halibut.

Nitrogen supersaturation danger level

104% or higher.

Monthly generator testing importance

To ensure emergency systems function during outages.

Ultrasonic flow meter advantage

Non-intrusive and extremely accurate.

Importance of volume in rearing units

To calculate fish density and tank exchange rate.