Largest female with downward curving leaf tips and browning lower leaves

[tszasz4u]

I am having trouble already with my largest female (?) plant, only five days into switching to 12/12. Her leave ends are all curling downwards and there are already browning leaves on the bottom of the plant. Upper leaves are a dark green, otherwise. I have decided to add just plan water (with pH down, at about half a ml per gallon of water). I had been using 4 ml of Monkey Juice flowering solution A & B with four liters of water (quarter strength), and 1 ml of pH down (my pH meter doesn't work), every watering. I am employing a 400 watt HPS.
All my other plants do not show this kind of response, even with similar feeding. I am using Miracle grow, with worm castings as a growing medium. I have a large fan that blows air into the grow area (in a large jacuzzi type tub 4 ft X 4ft X4ft. Air temp is probably at or near 80-85 F lights on, 65 lights off. Light is about 14 inches from canopy, with no indication of light burn. I believe the plants are a G-13 hybrid.

 

[bucktoothal]

hello
for starters you need a good Ph meter adding nutes will most likely lower your Ph, especially miracle grow types.
With out pictures it is really hard to tell whats is really going on. so I myself would flush, raise Ph to somewhere around 6.3-6.8. when using miracle grow type nutes always use no more than 1/2 strength. these types tend to nute burn the plants.