please help, leaves bleaching like crazy !

my friend has some nirvana superskunk plants three feet under one 1000 watt hortilux hps .
the plants are bleaching like crazy and a lot the very top leaves look very light and so do some upper internodes . they are currently in flower for about two weeks now .

pH = 5.8
ppm = 860
temp = 73

using gh flora three part = 3-2-1

thanks in advance !

not finding any answers ... anybody ?

oh well, he switched the bulb back to 400 hps ...

Distance from the light to the plant tops?

The light should be at least a couple feet from that bulb.

the light is three feet from the tops. but the bulb was switched back to 400 yesterday and they seem to be "greening up" . so how can i run the 1000 ? do i raise the ppm of the nutrient solution ? what do i do ? im going to get some skimpy buds if i cant run that 1000 watt bulb at least ... i'd like to run all 1800 watts of light that i have to get the most and highest quality buds ! thanks for the replies so far ! -peace-

strain = nirvana superskunk vegged for 5 weeks from seed under a small hydrofarm 400 watt metal halide
i had laying around

setup =
2 x radiant 8'' air cooled hoods
3 x hydrofarm ballasts (430 and 1000 plus a self contained 400 watt MH hydrofarm fixture)
1 x hydrofarm megagarden
1 x 800cfm inline fan
lots of gh nutrients