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How To Predict A Hatching Date
By keeping daily temperature measurements, you can predict hatching dates.
Time needed for the eggs to hatch and for the fry to be released is measured in temperature units (TU). A temperature unit is the average temperature for the day minus 32 degrees.
Example : The average temperature in a 24 hour period is 50 degrees F. Subtracting 32 from 50 equals 18 TUs for that period .
To predict the release date you need to do these things:
- Take water temperature every day
- Record the temperature like we did on the salmon check - up chart
- Calculate and record the number of TUs for each day. ( See example on chart below)
- Add each days' TUs to the total number from the days before. (See chart below)
- Predict the approximate hatch and release dates using the information provided below
In addition to keeping track of the temperature units each day, you will also need to monitor the following:
- Keep the temperature between 42 and 55 degrees F.
- Keep the pH level at about 7.0
- Keep the ammonia level less than 0.5 parts per million
- Keep track of your temperature units (TUs), so you can predict the release date
See the next page for calculating temperature units and release date.