light brown spots any ideas+pics

light brown spots on a few leaves, any ideas anyone? its lowryder #2 at about 4 1/2 weeks old, was feeding fox farms grow big for the first 3 weeks. could it be from the soil somehow? because i noticed this pro mix soil i got this crop was wayy spongy and retains water really well. any help is greatlyappriciated.

Those don't look like brown spots more like a lack of chlorophyll from being under fed. How much do you feed? Do you go by ppms I like that better than going by tsp!

PH balance could be the issue, can pick up a simple test kits at any hydro store or pet store. If the soil/water your using is too acidic/not acidic enough you'll have to balance it out accordingly (flushing soil using water with a correct ph level).