help help i have yellow on the leafs ?????

i have yellow on the end of the leafs wots this mean ?????????
water ?
temp ?
air ?
light ?
food ?
thanks lee

go to grow section mate, but I think it might be Nitrogen defficient, or too much nutrient intake AKA Nutrient burn.

If the leaf tips are burnt it could be over nitrogenated,wont know anything with that tidbit of info

[attachment=o127067]

Looks like Nitrogen defficient. :)