Question: do ales need a diacetyl rest?
Answer: For ale production, the fermentation temperature is usually 65 to 70 °F (18 to 21 °C), so temperature modification is not necessary. But the fermentation should still be “rested” at this temperature for two days to ensure proper diacetyl reduction. ... Once the yeast is removed, there is no way to get rid of the diacetyl.