Carolina 3M Petrifilm E.Coli/Coliform Count Plates - Manual (Page 6)

7. Lift the spreader. Wait at least 1 minute for the gel to solidify (fig. 7).
Figure 7
8. Incubate plates with the gridded side down in stacks of up to 20 plates.
Incubation time and temperature will vary according to the application
and equipment available.
9. Colonies on Petrifilm plates can be counted on a standard colony
counter or other light source (fig. 8). Bacterial colonies on Petrifilm EC
plates are red or blue because of the indicator dyes in the medium.
Refer to the Interpretation section on pg. 8 and 9 for more details.
Figure 8
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