Please, Help!!

Hey I have looked at the site for days with no luck finding my problem.
2nd week of flowering. 400 hps. temp 80. the bottem 2 fan leafs turned totally yellow in 2 days. and dropped off. 2 days later the next 2 did the same thing. no other sights of problems. no tip burn. the seeds were a good bag seed. that started autoflowering. ph is 7.5 I have added a small amount of sulfer to the soil. problem started before adding the sulfer. the sufler is slow acting too.
I'm using Blue mountain Orgainics nutes. super plant tonic should be here tomorrow.

Thanks In Advance

Ph should be 6.5. Are you giving the plant any fertilizer?

It was on 5-2-5 VEG orgainic. it's only been in flower for 8 days. I have given 1/2 & 1/2 the first nutes in flower. Flower 1-8-7. it's only this one plant. I have others of different seeds. it was this female and a male I pulled that stated this yellowing. it's getting worse next 2 sets are yelowing now.. Only I small amount of white on tips... I'll get a pic tomorrow. I'm going to flush to be safe. Going from CFL veg to HPS shouldn't have in affect?
I'm working on the Ph.(ie the sulfer) My water is higher then normal. after filtering. it's still high. like 7.5. I've heard of useing vinegar to lower Ph in water. I havnt tried it. anyone? anyone?Class Wake UP!!!!! way in on the Issue,please!!

also all I have is one of those cheap green 3 way, light,Ph,Most. meters. I know,I know I'm a cheap Bastard. what can I say , times are tuff... Are they even close to being aucurrate.
Damn ,no stoner spell check!!!! what the french..Toast!!!!LOL

BTW, Love the site... The info. Rocks!!!!! to the Idoit who posted the pic of how seeds arrive.. Take that shit down,DaHAAAA!!!
Peace Out!!!

Ok, Pics! anyone got any info..

Looks like simple nitrogen deficiency, add a bit of your grow nutes to fertilize sched. Do not pull the leaves off as they turn yellow, its ok to pull off after its totally shriveled and dried out, otherwise the plant is still using the leaf. They turn yellow because the plant is canabalizing the large leafs to feed itself.

Hey, Thanks for the info. Ok, I flushed. my soil has nutes in it.MG says it lasts 3 months. 2 1/2months old now. I didn't notice the bag said Nutes in soil. I wondered what them lil balls were.lol
Now what? Keep flushing??
I got my Super plant tonic today.. I use BMO's nutes. I was trying to go all orgainic. freaking soil!!!!!! trip to lowe's in my future! I'm going to mix my own...

I bet it is root bound.I used superthrive for the first 3 weeks. big ass roots... but to late to trans now...

Thanks in advance
gonna sample my first harvest... almost cured!!!! Whaoooo!!