help with one of my plants

[godonacid]

any one got any ideas what might be wrong with this plant, both are running from the same water source so im pretty sure its not to do with that, some sort of root issue is my thought but im not sure, any help would be appreciated.

pic from a week ago

 

pic from this week

 

for a bit more info, i am currently using an auto pot system, 2 x 10 inch pots (will be using somthing bigger next time) growing in fotoflake and using advanced nutrients range. currently at the end of week 4 and the start of week 5.

Edited February 15, 2007 by godonacid

[godonacid]

a couple more

 

bud from healthy plant

 

bud from unhealthy plant

[godonacid]

and one more

[WantDaChronic]

i'd be guessing that the plant that is yellowing has a salt build up or something along those lines if they were grown from cuttings that were taken from the same mother plant, but if those plants are 2 different strains or even the same strain but grown from seed, it is more than likely a pH problem or one nutrient locking out another

 

in any case, i think the best course of action would be to flush the system out with pH adjusted water, change the res over and flush it again to ensure all the nutes, salts, etc. have been flushed out completely. once that has been done, i would start the plants back up on low level nutrients, probably around 1.2EC while keeping a really close eye on them for about a week