Ph or over watering would be my guess
This 6 ounce spray bottle is all you need right now for watering , just mist around the base of the plant enough until it looks wet , and make sure it’s drain holes in the bottom of the cup . Honestly if you put your holes in a row like connect four diagonal around the cup on that angle it will also help oxygen get to the roots . But any spray bottle is all you need at the moment until after you transplant them later once they start growing .
ok ty Guys
Let me help you wade through all this.
PH should be 6.5-7.0 for soil, 6.5 -6.7 is optimum.
These small seedlings with little to no root system are too young and fragile to be placed in Foxfarm soil. You should have at least 4-5 true sets of leaves before exposing the new roots to minerals. 
I also totally advise to learn more about photo periods and how plants work in regards to using a 24/0 photo period. Bad idea, especially for a novice grower. Goes against nature.
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