Hi steelpulse. I think you're over-watering the plants. They are showing classic signs, eg droopy leaves, leaves falling off, leaves turning pale green etc. This happens because the roots are always saturated, don't get enough oxygen and can't feed the plants. The roots will eventually die. It's not a good idea to just have a watering regime like "every two days". Only water when the plants really need it. When you water, water well, so that water runs out the bottom of the pot, and then don't water again until the soil is dry at least two inches below the surface. Marijuana really benefits from dry periods between watering - it encourages strong roots, a strong healthy plant and lots of good quality bud. I think if you do this they will recover very quickly. Good luck
PS From the first pic it also looks as if your pots are quite small. Is it possible that your plants are root-bound? This will also lead to poor growth and your plants won't be getting the nutrients they need. Might be time to re-pot.
