Brown spots on my Cinderella 99s

[Crazy_Canuck]

I'm growing 4 plants in a 3 by 3' tent. To of them are sour amnesia and totally fine but my other two cinderella 99 have what look like burn spots on the upper leaves. The spots are through the leaves and can be scene underneath. I'm using a generic grow kit from Baux. 600w White leds sitting about 18 inches above the top.

What do you guys think? Any help is appreciated. Amateur grower on his second crop.

 

[Crazy_Canuck]

Oh by the way, the following girls are growing in soil using a 2 stage nutrient system by Green planet in addition to terpinator 0-0-4. Lights are 12 on and 12 off. The pails there growing on are about 25 litres and I feed them 2 litres of water when the soil is bone dry about an inch from the surface. 2 litres each each feed and I flip back and forward with nutrient and without.