Mechanical Systems in Aquaculture Exam Questions

Downsides of surface water

• HUGE seasonal variation in TEMPERATURE, DISSOLVED OXYGEN AND FLOW! (spring melt heavy rain, droughts etc. 

• Upstream inputs can change farms (POLLUTION) i.e golf course.

Domestic (Municipal/land based).. why is it rare?

IT IS VERY EXPENSIVE.

Why isn’t domestic water used in a fish hatchery?

Chlorine and fluoride kills fish and its expensive. 

How many bulbs are in a UV light?

6 (effluent system)

what state does ranching?

Alaska (1970’s)

Flow-through/serial reuse

Water flows through one or more rearing units then exits

RAS - Recirculating Aquaculture System

79.5% of water reused - biofiltrations, degassing, uv

The difference between flow through (reuse) and RAS (recirculating) is?

Reuse: water comes in, flows through multiple tanks and leaves NEVER to be used again

RAS: water cycles are in REUSE - it flows through one or more ponds and is reconditioned (biofiltration)

Volume of a cube

length x width x height

Cylinder:

3.14 x (radius squared) x height

Why is volume important to know?

DENSITY!

Exchange rate

is the total time it takes a tank to turnover (L/Min)

 2 types of flow in a circular tank:

primary rotating flow and secondary radial flow.

What are the 3 types of impellers?

closed, semi open and open impellers 

Closed Impeller

2 shrouds → high head

Clean water (no debris)

Semi Open Impeller

1 shroud → handles some debris

Medium solids / higher capacity

Open Impeller

No shrouds → handles “trash”

Dirty water / low pressure

Pressure Release Valves

Must be installed between your pump and the first valve

Know pump curves:

12 stg (#of impellers) ¾ hp (watch capacity)

What is the difference between a thermolicer and a hydrolicer?

A thermolicer uses a jet of warm water to get rid of sea lice, whereas a hydrolicer uses a freshwater jet to get rid of sea lice.