Tiny Brown/Yellow Spots on My Purple Kush. Help!

Hey guys I'm pretty new to the forum and this is my second grow. I have been growing this purple kush for a while and I just put the plant under my 400w HPS on 12/12 for flowering about a week ago.

About a week ago right around the same time as putting the plants under the HPS, the PK started getting tiny little brown and yellow spots all over the leaves and the brown spots can be seen from the underside of the leaves. It started at the oldest fan leaves and is now moving to the whole plants fan leaves. I am not sure what it is thats causing it.

There are also two other plants growing, Sour D and White Widow, and they are doing fine. They are on the same schedule and the same nutes as the PK.

They are growing in 12" pots with a cocoa coir/perlite mix. I use the Coco A and B nutes, SensiCal (Cal Mag), Rhizotonic, and Cannazyme each water, and ph controls when needed.

I just took the ph of the coco yesterday and it was at around 7.0. I added some ph down to the water and watered. I cut off some of the old dieing leaves and it is just getting worse. I am not sure what to do.

Check out the pictures so you can see what I'm talking about. The first two are on the plant and the last is clipped. Please help asap.

whats your ph/ppm at and what fert are you using. room temp? hunidity level? type of bulb?

I will have to recheck my Ph but last I checked before the ph down, it was at 7.0. As I said before I use the Coco A and B nutes, SensiCal (Cal Mag), Rhizotonic, and Cannazyme each water, and ph controls when needed. The room temp is around 75-80 on average and the humidity is around 20%. The bulb is an eye hortilux super hps 400w.

I haven't started up a flower nute water yet but i am thinking maybe I should use some different nutes now that I am in the flowering phase.

it might b nute burn but it almost looks like a deficient

mn deficiency

Check this out.Nutrient Knowledge Article's Merged.It might be "leaf rust".but i'm not 100% sure.

I was thinking it might be leaf rust but I wasn't sure. I have never seen rust before so I have no idea what it is. I was also thinking it could be a magnesium deficiency but that is HIGHLY unlikely as I am using a calcium magnesium nute Sensi Cal.

looks like you have dead tissue whats your feeding like and what is the PH?

I have the exact same problem with my purple kush did you figure out what it is becouse i'm 3 weeks into flowering and 11 of the 14 plants have it. I'm using the canna line and I dont know if I need to flush from nute burn or add cal mag for magnesium deficiancy

i am haveing some problems with my plants could someone take a look at my pics please because i dont have a clue what is wrong i think its nute burn but i noticed my ph was off it was only at 5.5 to 6.1 in the soil i have a 105w cfl 6400k could someone help me please A.S.A.P

i noticed my purple haze has a like a silver halo on 1 of the leaves a few weeks back then the halo turned brown and now i have spots of yellow brown spots all over my plants i know my ph is wrong i just got a soil tester and it was from 5.5 to 6.1 i know that is wrong my ph its ment to be 7 right ??? this is only my 2nd grow so im a nube i have a 105w cfl 6400k is that enougth for a 1 meter square grow room ??? and im useing bio bizz grow fert plus i think it might be nute burn because i only warter once every 3 days but it looks like its takeing ages for the soil to dry out its only 79f in my grow room is that ok ??? how can i get my temp up ?? put another light in ?? these pics were took quick on my phone im trying to get a camera to put better pics up but any help would be good
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does any one know how granddady looks when it starts to turn purple?

my bad granddaddy