A little help please.

Hi, I'm having a bit of trouble with my grow (white widow). I'm getting black spots and necrosis on the fan leaves and major yellowing, i havn't a clue what is going on with them and don't wanna bin the plants if i can help it.

600w sunmaster grow lamp
coco (85%) with perlite (15%)mix
air flow and temps are good
PH 5.8, dutch pro A&B grow food (2mil per litre)

I started these plants off from seed (first time), i usually use clones and had no problems.
The plants have just turned 5 weeks old and the largest is around 12" tall, they have been dropping fan leaves like crazy and look a bit sickly.
I was planning to switch the timings to 12/12 at the end of this week but don't know if i should if they are having problems but i don't wanna miss my Christmas smoke.

Here's some pics of the problem any help is appreciated.



I've had to remove a lot of leaves recently so the plants look a little worse now than in the pics, the little leaf in the last pic is one that i took off today and is a common trend over all the plants apart from one that is unaffected.

Also a friend of mine say's that my plants are doing this because they naturally want to turn and grow buds rather than veg, is there any truth in that ?

I wish I had the answer but in the meantime take a good look at the leaves with a loupe and maybe you can rule out any type of insect infestation, if there is nothing crawling around then it's some kind of deficiency, maybe magnese....but if your PH is 5.8 it shouldn't be getting locked out.

Take a look at this until someone smarter comes along.

http://www.icmag.com/ic/showthread.php?t=11688

Thanks for the guide mate.
Yeah this grow is doing my head in, i've been racking my brains to try and find out what could be causing the yellowing and black spots.
There is one thing that i have noticed though and that is that my nutrients (dutch pro) both A&B have a cloudy appearance and with white bits floating around in them they are only around 8 months old and still 3/4 full.
I've compared to a friends nutrients from the same maker and his are clear and with no "floaters", could this be causing my problems a set of bad nutes bought from the shop?

You either aren't feeding them enough nitrogen..or you have been vegging them with salty nutes for a while and they have gotten them self nute lock out. Water will work by itself to flush but i've used sledghammer in the pass to flush them and it turned them around within a few days.

Well, i've switched my "BAD" nutes out for my friends "GOOD" nutrients and they look a bit more alive (perky) and i've noticed a lot more growth on the secondary arms more than anything else, fingers crossed they will pull through.
I've also swapped out my bulb from a 600w full spectrum grow lamp to a 600w HPS, just incase that had anything to do with it.
As far as the PPM meter is concerned, i don't have one, i've been eyeing one up on Amazon to purchase but don't have two penny's to rub together atm, but i live in a soft water area so PPM should be low.

Your plant has aids,naw seriously it looks like manganese deficiency