Recirculating SystemsRecirculating Systems

What you really need to knowWhat you really need to know

What Is The Goal?What Is The Goal?

To produce fish in a cost To produce fish in a cost effective manner where the effective manner where the environment is controlled environment is controlled

through water treatment and through water treatment and recirculationrecirculation

Putting the Pieces TogetherPutting the Pieces Together

•ComponentsComponents

•SetupSetup

•OperationOperation

•Water QualityWater Quality

Basic System ComponentsBasic System Components

• Culture Tank(s)Culture Tank(s)

• Solids RemovalSolids Removal

• BiofilterBiofilter

• OxygenationOxygenation

• PumpPump

• Temperature ControlTemperature Control

• Fine & Dissolved Solids RemovalFine & Dissolved Solids Removal

• DisinfectingDisinfecting

Types of Culture TanksTypes of Culture Tanks

Types of TanksTypes of Tanks

Solids RemovalSolids Removal

• Settleable solidsSettleable solids– solids that will generally settle out of the solids that will generally settle out of the

water within 1 hour under still conditionswater within 1 hour under still conditions

• Suspended solidsSuspended solids– will not settle to the bottom of the fish will not settle to the bottom of the fish

culture tankculture tank

• Fine and dissolved solidsFine and dissolved solids– < 30 micrometers< 30 micrometers

Settleable SolidsSettleable Solids

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

Solids RemovalSolids Removal

Settling BasinSettling Basin

Settling Basin DesignSettling Basin Design

Settling Basin and Biofilter Settling Basin and Biofilter ReturnReturn

Suspended SolidsSuspended Solids

• Can Be Removed By:Can Be Removed By:– Screen FiltrationScreen Filtration– Mechanical Filtration (sand or pelleted Mechanical Filtration (sand or pelleted

media)media)

Upflow Sand FilterUpflow Sand Filter

Bead FiltersBead Filters

BiofiltrationBiofiltration

• Removes Metabolic Waste ProductsRemoves Metabolic Waste Products– AmmoniaAmmonia– NitriteNitrite

Biological FiltrationBiological Filtration(Nitrification)(Nitrification)

• Trickling Filters Trickling Filters

• Bead FilterBead Filter

• Rotating Bio-Contactor (RBC)Rotating Bio-Contactor (RBC)

Trickle FilterTrickle Filter

Packed TowerPacked Tower

Filter MediaFilter Media

Surface Area of Various Surface Area of Various MediaMedia

Bead FilterBead Filter

RBCRBC

Rotating Bio-ContactorRotating Bio-Contactor

OxygenationOxygenation

•Aeration and DegassingAeration and Degassing

•Pure Oxygen InjectionPure Oxygen Injection

In most cases, a system’s ability to add dissolved oxygen to water will become the first limiting factor in a system’s fish carrying capacity.

Regenerative BlowerRegenerative Blower

Air StonesAir Stones

Downflow Bubble ContactorDownflow Bubble Contactor

PumpPump

Pump selection is based on the amount of

recirculation necessary to maintain good water

quality.

Related to feed input, number, size & species of fish

Temperature ManipulationTemperature Manipulation

Dissolved Solids ControlDissolved Solids Control

• Can Be Removed By:Can Be Removed By:– Foam FractionatorFoam Fractionator– Water ChangesWater 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

Foam FractionatorFoam Fractionator(Protein Skimmer)(Protein Skimmer)

Things to think aboutThings to think about

Putting it all togetherPutting it all together

Where to StartWhere to Start

• Inspect PartsInspect Parts

• Identify and Label PartsIdentify and Label Parts

• Read DirectionsRead Directions

• Assemble System Assemble System WithoutWithout Glue Glue

• Double Check 1-way Valves etc.Double Check 1-way Valves etc.

• GlueGlue

Start-Up Break In PeriodStart-Up Break In Period

• Fill With WaterFill With Water

• Check For Leaks & RepairCheck For Leaks & Repair

• Let run for a few days and watch for Let run for a few days and watch for new leaksnew leaks

• Remove ChlorineRemove Chlorine

Biofilter InitiationBiofilter Initiation

• Check AlkalinityCheck Alkalinity

• Start adding SMALL amounts of Start adding SMALL amounts of household ammoniahousehold ammonia

• Bacteria should begin to colonize Bacteria should begin to colonize filterfilter

• Run system for 2-3 weeksRun system for 2-3 weeks

Biofilter Initiation Option #2Biofilter Initiation Option #2

• Add 20-30 small to medium fishAdd 20-30 small to medium fish– Use a reputable fingerling dealerUse a reputable fingerling dealer– Check fish for parasites and disease Check fish for parasites and disease

prior to adding them to the systemprior to adding them to the system– Acclimate fish to receiving tankAcclimate fish to receiving tank

Calculate FeedCalculate Feed

• Feeding rates based Feeding rates based on on – Fish SpeciesFish Species– Fish SizeFish Size

Tilapia Stocking and Tilapia Stocking and FeedingFeeding

Calculating Feed AmountCalculating Feed Amount

• ExampleExample

• 100 fish weigh 10 pounds total 100 fish weigh 10 pounds total

• Approximately 45 grams eachApproximately 45 grams each– According to chart use 3.2% of body wt.According to chart use 3.2% of body wt.– 10 lbs x 0.032 = .32 lbs or 145 grams10 lbs x 0.032 = .32 lbs or 145 grams

• Feed 145 grams splitting feed into Feed 145 grams splitting feed into several feedingsseveral feedings

Recalculating FeedRecalculating Feed after 7 days after 7 days

• Sample 25 fish and calculate total wt.Sample 25 fish and calculate total wt.– 25 fish weigh 1314 grams 25 fish weigh 1314 grams – 1314 grams / 25 fish = 52.6 g/fish1314 grams / 25 fish = 52.6 g/fish– 100 fish x 52.6 g = 5260g or 11.6 lbs100 fish x 52.6 g = 5260g or 11.6 lbs

• New feed rate = 5260 g x 0.032 = New feed rate = 5260 g x 0.032 = 168g168g

Feed Conversion RatioFeed Conversion Ratio

• Growth = 1.6 lbs using 2.24 lbs of Growth = 1.6 lbs using 2.24 lbs of feedfeed

• Feed Conversion Ratio = 1.4 : 1Feed Conversion Ratio = 1.4 : 1

• Now that you have a feed conversion Now that you have a feed conversion ratio you can also calculate new feed ratio you can also calculate new feed rates based on this ratiorates based on this ratio

Calculating New Feed Rate Calculating New Feed Rate Based on FCRBased on FCR• 10 days feeding at the new rate 10 days feeding at the new rate

• 168g x 10 =1680 g168g x 10 =1680 g

• 1680 g / 1.4 = 1200 g new growth1680 g / 1.4 = 1200 g new growth

• New total weight =New total weight =– 1200 g + 5260 g = 6460 g1200 g + 5260 g = 6460 g

• New daily feed rateNew daily feed rate– 6460 x .032 = 207 g6460 x .032 = 207 g

• Recalculate FCR regularly (1-2 months)Recalculate FCR regularly (1-2 months)

Water Quality After FeedingWater Quality After Feeding

• Watch ammonia levelsWatch ammonia levels

• Prepare water for partial changePrepare water for partial change– 2-3 55 gallon barrels2-3 55 gallon barrels

• Change 5-10% of water every 1-2 daysChange 5-10% of water every 1-2 days

• Track feed, DO, Ammonia, Nitrite, pH Track feed, DO, Ammonia, Nitrite, pH and alkalinityand alkalinity

• Once system is stable add more fishOnce system is stable add more fish

Adding More FishAdding More Fish

• Determine how many fish system Determine how many fish system can handlecan handle

• Look at capacity of biofilterLook at capacity of biofilter– based on surface area of mediabased on surface area of media

• Continue to monitor and feedContinue to monitor and feed