PLEASE HELP!! is this nute burn, ph crazy or some other prob

here are some pics of my sickly plants, leaves firstly started to curl and became crispy, they have now gone yellow with brown pathches and some have fallen. still producing new growth but now some of that has started going the same, see pics
PLEASE Help, this is my first grow.

They are growing under a 600w HPS in an enclosed enviornment with fans in and out, currently temp average about 20 c and ph level 5 to6, . Any ideas on what I could try?

what are you feeding it?

http://www.marijuana-seeds.net/Thanks-ThankYou.htm

could be overwatering and feeding.

Have been feeding them the following nutes;
Dutch Pro - multi total, take root & original grow
I also increased the amount water when the leaves went crispy

Do you think giving them a flush will help?

have given them a good flush and left to drain off. but what do I do now?

it doesn't appear to be classical nute burn, no

squarepush3r said:

it doesn't appear to be classical nute burn, no

Click to expand...

so what u reckon it is? could they have nute lock and if so what do I do now?

My plants have the same problem, hope someone can shed some light on this.

checked them this morn and there looking slightly better after the flushing, fingers crossed.
would fert be recomended now