Pics of a sick leaf, any ideas???

[greenthumberish]

Alright, here they are...i just tried to post the this twice, and both times the browser froze...so wish me luck. Here's the leaf, any ideas on the sickness that causes this? Im out of ideas.

 

[greenthumberish]

finally! It posted...so here are the facts
Plant is a clone, been in flowering 6 weeks, plant was a "gift" from another patient and when I got it, it was sick.
Medium: FFoF
Fertz: since problem began, i've given light epsom salts,1/4 strength bat guano 10-3-1, light flowering fish ferts 1/4 strength of 0-10-10, and added 1 teaspoon per gallon of dolomite lime
Pot: 5 gallon homer bucket
light: 1000watt hps
Grow conditions immaculate flowering room. no light leaks
Temp: 88 peak(rarely) commonly 80, low 70
Humidity peak 68%, stays 45 to 50% regularly.
At first I thought it was PH deficiency, but i checked dirt PH and runoff, was around 6.2, and changed water PH to 6.6 before watering several times. Normally water is 6.4, but figured it maybe nute lockout due to PH being too low for P to be absorbed. The only time the plant started to 'spring back' was when I gave it a dose of N, and that kept the new leaves from getting crunchy. Any ideas? I've been treating all the plants with the same fertz, and this is the only one that's behaving this way. Comments and suggestions appreciated! Thanks

 

[DirtySouth]

Plants def. in phosphorus grow slowly and are stunned w/ small leaves. The older leaves are affected 1st. !st they turn dark green and become weak. The leaves develope dull blue or purple hues( ya got em) . The edges of the leaves turn tan/brown and curl downward as the def. works its way inward.

Are you experiencing dark green fan leaves w/ a purple or dull blue hue on? Maby purpling (recent) on stems or petioles?

 

[greenthumberish]

Alrighty I've got nothing to lose with that paticular plant, so I gave it a higher dose of P to see what will happen...either the plant will die, or it wont Thank you for the suggestion DS...I am assuming that I didn't feed it enough then...but we'll see