Leaves curling up, edge yellowing, thinning

Hi,
my friend is trying a first grow attempt in soil. Strain is A Quick One autoflowering. Just over 3 weeks since germination. Temperature in grow room ranges from 24 - 27 deg Celsius. No information on humidity or soil pH (hasn't got meters). The plants were given a weak 25% mix of Hesi Grow 3 - 2 - 4 about a week before signs of trouble started. Soil manufacturers say it is 15 - 10 - 15 with a pH of between 5 - 6.5.
Basically the pics speak for themselves, but not experienced enough to know what they say . We looked at some pics but couldn't tell what problem is. Possible overwatering?

some of them look heat stress , but your temperatues are good soo i can't really tell .
how's your humidity ?

Lysergicpt said:

some of them look heat stress , but your temperatues are good soo i can't really tell .
how's your humidity ?

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that's what I first thought, but yeah temp looks good. don't know about humidity, because no hygrometer but the plants have been misted now and eased off on the electric fan.

Bingo...stop misting your plant! Not sure why people do that!!!???