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Formalin Drip Treatment For Eggs in Bell Jar Incubators
Disclaimer: • This presentation is a formalin treatment example for eggs in
bell jar incubation systems. This example should be used as a basic guideline and not meant to be specific to a farm or hatchery. It is important to develop operational procedures that relates to an individual farm or hatchery.
Calculating Constant Flow Treatments • FDA approves 1000-2000 µL formalin concentration for
egg treatments in a flow through system • DO NOT treat if fry are present or if eggs are close to
hatching.
Step 1. Determine Volume of Water in Trough/Head Tank
• Why? To make sure that at least one exchange of water happens in the trough during the 15 minute drip treatment.
Head Tank Example: Inflow = 5gpm 5gpm x 15min = 75gal water flow through in 15min Trough Volume = 72in x 11in x 12in =9,504in3
231in3 in 1 gal so 9,504in3 / 231in3 =41.1gallons tank volume…
What does this mean? Therefore, in 15 minutes, 75 gallons has flown through the head tank (which we calculated is 41gallons in volume). This means the head tank water has been exchanged at least once in 15 minutes.
Step 2. Calculate Amount of Formalin
• Amount of Formalin to add to inflowing water over the course of 15 minutes:
75 gallons (total water flow in 15 minutes) x 0.00378 g/gal (Correction Factor to accurately get treatment in ppm) x 1667ppm (Recommended Formalin Treatment) x 1 (100%) Active Formalin = 472.6ml of Formalin
Step 3. How to Disperse Treatment over 15 minutes
To disperse treatment into head tank, the easiest way is to use a chicken waterer and drill a hole in the outer rim. What size hole to drill to ensure 15 minute drip?
We calculated that we need 472.6ml formalin to drip out in 15 minutes to achieve desired treatment. 946ml total volume needed – 472.6ml formalin= 473.4ml of water to add with Formalin
According to Introduction to Fish Health Management , a 1/16th inch hole in a chicken waterer delivers 946ml of liquid in 15 minutes. It is a good idea to verify and test your chicken waterer to insure 15 minutes is the total time it takes to disperse the volume above. Simply use water to test this.
Step 4. Add Treatment + Water
• Wear a chemical respirator mask to add 472.6ml of formalin treatment to a chicken waterer.
• Now add in 473.4ml of water to
the chicken waterer to bring the total volume up to 946ml of total liquid in the waterer (formalin + water)
It is a good idea to mark out on the chicken waterer where the total volume of 946 ml (formalin + water) comes to on the jar. This way, next time you need to treat, you can simply measure out the 473ml of Formalin to the jar, then add enough water to reach your mark.
Step 5. Treatment Placement • Place chicken waterer to drip into
head tank and begin treatment. Make sure it is stable and will not tip over.
• Placement of drip should be situated near inflowing water or air diffuser so that the treatment is well mixed in the head tank before flowing to eggs.
• Be sure to monitor treatment. • Proactively treat eggs every few
days or daily if fungus is observed. This is also based on individual hatchery protocols.
Questions or More Information…
Contact UWSP-NADF Outreach Specialist: Emma Wiermaa
ewiermaa@uwsp.edu
Resources & References University of Wisconsin-Stevens Point Northern Aquaculture Demonstration Facility
aquaculture.uwsp.edu
Introduction to Fish Health Management United States Department of the Interior
Fish and Wildlife Service Second Edition 1995
American Fisheries Society Fish Culture Section
Guide to Using Drugs, Biologics and other Chemicals in Aquaculture & Treatment Calculator
http://fishculture.fisheries.org/working-group-on-aquaculture-drugs-chemicals-biologics/wgadcb-resources-tools/guide-to-using-drugs-biologics-and-other-
chemicals-in-aquaculture/
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