Plants turning yellow, nute problem? Any help appreciated, my first grow

Check your runoff water for the ec level. Make sure your ph is also coming out at 6.3 for veg. This is how you diagnose your problems. Also fabric planters need more water as when they fill with roots they can become harder and harder to get the water/food to all the roots. Water channeling and leaving dry areas in your root zone. Dry roots can form brown spots on your plants, usually mid to near the top of the plant. Cheers