Hey, thanks for the quick replies. In response to torog:

I gave them epson salts last week and this week (and will continue to do so till i see a change). Im using bottled water from a local spring (so it should be ok, but ill buy a ph testing kit and check that and the soil tommorow). I can't post a pic of the plant, because my camera is broke atm, also they are decent seeds cost £60 femminized W.W and bob marleys best.. so they have good genetics. And its not fert burn from the soil as it has very minimal only neccessary nutes in it.. not enough to burn them anyways.. also the other plants that im growing are fine.. watered with the same water and used the same soil..

In response to Imotep:

The plants are about 25cm tall they aint very tall yet just real bushy.. its not the leaves dropping off its definatly some kinda deficiency theyre like yellow/rustyish looking spots on there.. the plant is getting light at the bottom so its not down to that i dont think anyways. Its got excelolent drainage.. (50% soil 50 % perlite) its got proper ventilation so thats not a problem. Not to sure about the temps though, will purchase a thermometer tommorow and find out..

so hope this helps a bit more. Thanks again.