Help! Whats wrong with my plants?

[420shooter]

This is only really showing up on 2 plants that are the closest to the cold wall in the room. The others look pretty good but may be just starting to show the same signs. Is this a deficiency or could it be from the colder temps by the wall?
How long has this problem been going on? 1 week
Are you growing in a PVC grow tent? no
What system are you running? Smart Pots 3gal
What STRAIN are you growing? BOG Sour Strawberry
What was the establishing technique? seed
What is the age of your plants? 3 months
How long have they been in there mixture they are in now? 2 months
How tall are the plants? 40 inches
What PHASE are the plants in? flowering
What substrate/medium are you using? Pro-mix HP
What Nutrient's are you using? bongaloids guano recipe
How often are you feeding? plain water only
How often are you giving nutrients? plain water only
When was your last watering? yesterday
What size bulb are you using? 1000w hps
How old is the bulbs you are using? 3 months
What is the distance to the canopy? 2 feet
What is your RH Factor(Relative Humidity)? 50%
What is the canopy temperature? 77-79f
What is the Day/Night Temp? 65-73f
Tell us about your ventilation, intake exhaust and when its running and not running ?Aircooled when lights are on
Is the fan blowing directly at plants?no
Is your water HARD or SOFT? hard
What water are you using? RO
If using RO,Distilled,mineral water, what is the ppm/EC/TDS without any additives? 27ppm
Are you using water from a water softener? yes RO filtered
Has plant been recently pruned, cloned off of or pinched? no
Have any pest chemicals been used? no
Are plant's infected with pest's? no

 

[Brand...]

really does not look so bad, perhaps add some more (P)

 

[Hash Zeppelin]

looks they are starting to finish. what week of flowering are they in. said two months in current mix so I am guessing that they have been in flower almost that long right?

 

[Ultra Current]

I see that you are just using water with your promix. Tell me more about your guano recipee and why it wouldnt run out after 2 months. Also what is the pH of your water when you water your plants. What is the pH of your recent run off?

Without knowing that information, id say that you need nutes and a possible pH adjustment. Guanos dont last forever in my experience but i guess that would depend on how much you used.

 

[grapeman]

nothing's wrong. Raise your lights 6"

 

[420shooter]

A little more info.
Guano recipeer gallon
1/3 cup high N Mexican bat guano
1/2 cup high P Indonesian bat guano
1tbs kelp meal
1tbs greensand
These are in 3 gal Smartpots
ph is 6.5
no runoff
yellowing started at the top with the large fan leaves

plants were @ 28 days of 12/12 when pics were taken
I'm only seeing this on the 2 largest plants that also happen to be the closest to the cold wall.
The yellow leaves are starting to turn purple now. Could the cold temp (63f) at the top of the pots lockout P?
I've given 1 watering of high P guano tea since the pics were taken and it seems to have slowed the yellowing on new leaves down.
Thanks for the help.
I'll get more pics tonight.