1. Recirculating Systems
What you really need to know

2. What Is The Goal?
To produce fish in a cost effective manner where the environment is controlled through water treatment and recirculation

3. Putting the Pieces Together
Components
Setup
Operation
Water Quality

4. Basic System Components
Culture Tank(s)
Solids Removal
Biofilter
Oxygenation
Pump
Temperature Control
Fine & Dissolved Solids Removal
Disinfecting

6. Types of Culture Tanks

7. Types of Tanks

8. Solids Removal Settleable solids Suspended 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
< 30 micrometers

9. Settleable Solids Can be removed by: Well placed drains
Sedimentation tank (clarifier)
Mechanical filter (granular or screen)
Swirl separator

10. Solids Removal
Settling Tank

11. Settling Basin

12. Settling Basin Design
Weir

13. Settling Basin and Biofilter Return

14. Suspended Solids Can Be Removed By: Screen Filtration
Mechanical Filtration (sand or pelleted media)

15. Upflow Sand Filter

16. Bead Filters

17. Biofiltration
Removes Metabolic Waste Products
Ammonia
Nitrite

18. Biological Filtration (Nitrification)
Trickling Filters
Bead Filter
Rotating Bio-Contactor (RBC)

19. Trickle Filter
Bioballs

20. Packed Tower
Trickle Filter
Trickle Filter
Trickle Filter

21. Filter Media

22. Surface Area of Various Media

23. Bead Filter

24. RBC
Rotating
Bio-Contactor

25. Rotating Bio-Contactor
RBC
RBC

26. Oxygenation
Aeration and Degassing
Pure Oxygen Injection

27. 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.

28. Regenerative Blower

29. Air Stones
Fine Bubble
Medium Bubble

30. Downflow Bubble Contactor

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

32. Temperature Manipulation
Heater
Chiller

33. 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

34. Foam Fractionator (Protein Skimmer)

35. Break Time

36. The Set Up
Things to think about

37. Putting it all together

38. Where to Start Inspect Parts Identify and Label Parts Read Directions
Assemble System Without Glue
Double Check 1-way Valves etc.
Glue

39. 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

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

41. Biofilter Initiation Option #2
Add 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

42. Calculate Feed
Feeding rates based on
Fish Species
Fish Size

43. Tilapia Stocking and Feeding

44. 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 = .32 lbs or 145 grams
Feed 145 grams splitting feed into several feedings

45. 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 = 168g

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

47. 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 g = 6460 g
New daily feed rate
6460 x .032 = 207 g
Recalculate FCR regularly (1-2 months)

48. Water Quality After Feeding
Watch ammonia levels
Prepare water for partial change
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

49. 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

50. Eat Fish