Leaves curling upwards, Can't figure out the issue, thank you for any advice!

Aloha, these seedlings were started about 2 weeks ago, everything seemed to be going smooth and they are still growing nice but I have noticed a strong upward curl taking place on two of the seedlings. I have more than adequate air going in each bucket, light seems sufficient for their age and there is a nice mellow air movement. PH is good and I'm keeping the PPM around 450 Any advice or tips to remedy this would be super appreciated.
Mahalo~
 

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it looks like too much light maybe the light is bouncing off the white buckets and pumping too much into them. Are all of them doing it?
Not all of them, just two so far but maybe a 3rd slightly showing signs. Yeah I thought that too, They are super young! Maybe I'm overdoing it?
 
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