Recirculating Systems

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Recirculating Systems

• What you really need to know

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What Is The Goal?

• To produce fish in a cost effective manner where
  the environment is controlled through water
  treatment and recirculation

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Putting the Pieces Together

• Components
• Setup
• Operation
• Water Quality

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Basic System Components

• Culture Tank(s)
• Solids Removal
• Biofilter
• Oxygenation
• Pump
• Temperature Control
• Fine Dissolved Solids Removal
• Disinfecting

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Types of Culture Tanks
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Types of Tanks
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Solids Removal

• Settleable solids
• solids that will generally settle out of the
  water within 1 hour under still conditions
• Suspended solids
• will not settle to the bottom of the fish culture
  tank
• Fine and dissolved solids
• lt 30 micrometers

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Settleable Solids

• Can be removed by
• Well placed drains
• Sedimentation tank (clarifier)
• Mechanical filter (granular or screen)
• Swirl separator

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Solids Removal
Settling Tank
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Settling Basin
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Settling Basin Design
Weir
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Settling Basin and Biofilter Return
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Suspended Solids

• Can Be Removed By
• Screen Filtration
• Mechanical Filtration (sand or pelleted media)

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Upflow Sand Filter
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Bead Filters
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Biofiltration

• Removes Metabolic Waste Products
• Ammonia
• Nitrite

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Biological Filtration(Nitrification)

• Trickling Filters
• Bead Filter
• Rotating Bio-Contactor (RBC)

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Trickle Filter
Bioballs
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Packed Tower
Trickle Filter
Trickle Filter
Trickle Filter
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Filter Media
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Surface Area of Various Media
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Bead Filter
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RBC
Rotating Bio-Contactor
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Rotating Bio-Contactor
RBC
RBC
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Oxygenation

• Aeration and Degassing
• Pure Oxygen Injection

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In most cases, a systems ability to add
dissolved oxygen to water will become the first
limiting factor in a systems fish carrying
capacity.
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Regenerative Blower
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Air Stones
Fine Bubble
Medium Bubble
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Downflow Bubble Contactor
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Pump
Pump selection is based on the amount of
recirculation necessary to maintain good water
quality.
Related to feed input, number, size species of
fish
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Temperature Manipulation
Heater
Chiller
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Dissolved Solids Control

• Can Be Removed By
• Foam Fractionator
• Water Changes

Fine suspended solids increase the oxygen demand
of the system and cause gill irritation.
Dissolved organic solids (protein) can contribute
significantly to the oxygen demand of the total
system
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Foam Fractionator(Protein Skimmer)
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Break Time
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The Set Up

• Things to think about

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Putting it all together
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Where to Start

• Inspect Parts
• Identify and Label Parts
• Read Directions
• Assemble System Without Glue
• Double Check 1-way Valves etc.
• Glue

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Start-Up Break In Period

• Fill With Water
• Check For Leaks Repair
• Let run for a few days and watch for new leaks
• Remove Chlorine

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Biofilter Initiation

• Check Alkalinity
• Start adding SMALL amounts of household ammonia
• Bacteria should begin to colonize filter
• Run system for 2-3 weeks

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Biofilter Initiation Option 2

• Add 20-30 small to medium fish
• Use a reputable fingerling dealer
• Check fish for parasites and disease prior to
  adding them to the system
• Acclimate fish to receiving tank

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Calculate Feed

• Feeding rates based on
• Fish Species
• Fish Size

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Tilapia Stocking and Feeding
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Calculating Feed Amount

• Example
• 100 fish weigh 10 pounds total
• Approximately 45 grams each
• According to chart use 3.2 of body wt.
• 10 lbs x 0.032 .32 lbs or 145 grams
• Feed 145 grams splitting feed into several
  feedings

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Recalculating Feed after 7 days

• Sample 25 fish and calculate total wt.
• 25 fish weigh 1314 grams
• 1314 grams / 25 fish 52.6 g/fish
• 100 fish x 52.6 g 5260g or 11.6 lbs
• New feed rate 5260 g x 0.032 168g

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Feed Conversion Ratio

• Growth 1.6 lbs using 2.24 lbs of feed
• Feed Conversion Ratio 1.4 1
• Now that you have a feed conversion ratio you can
  also calculate new feed rates based on this ratio

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Calculating New Feed Rate Based on FCR

• 10 days feeding at the new rate
• 168g x 10 1680 g
• 1680 g / 1.4 1200 g new growth
• New total weight
• 1200 g 5260 g 6460 g
• New daily feed rate
• 6460 x .032 207 g
• Recalculate FCR regularly (1-2 months)

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Water Quality After Feeding

• Watch ammonia levels
• Prepare water for partial change
• 2-3 55 gallon barrels
• Change 5-10 of water every 1-2 days
• Track feed, DO, Ammonia, Nitrite, pH and
  alkalinity
• Once system is stable add more fish

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Adding More Fish

• Determine how many fish system can handle
• Look at capacity of biofilter
• based on surface area of media
• Continue to monitor and feed

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Eat Fish