My question is

I'm on my 2nd grow now and my plants dont seem to produce very much. I check my ph and ppm and keep it in range. I use general hydroponics nutrients with big bud and calmag and follow guidelines but still not having good harvest? Can you help me please? I'm using a standard potting soil. Is there a specific soil I should be using after transplanting? Or in the flowering stage? My plants grow well in veg stage but not in flowering stage does not produce much I had 9 plants and barely got 2oz in total. This is week 4 of flowering. My led lights have 2 settings veg and bloom, should I be doing both at same time when flowering or just the bloom setting?