newbie grower needs help leafs changing color stem changing color

hey hows it smoking? first time grower, ive had this plant since 9*29*08 and it is about 10" tall. plant seems healthy nice dark green leafs on most the plant. but i just notices that the tips on almost every leaf even the new ones that are growing in have turned a yellowish brown. ive also noticed that the main stem of the tree has turned a darkish brown. im starting to see that the top fan leafs are starting to turn a little redish purplish. i am growing in soil what i am growin is a bahi black head it is a clone and i got it about 3 weeks ago. im getting ready to go into flowering soon. i am using mircle grow soil not great soil i know since the nute levels are so low. i mixed in a litle ROSE food pebele things into the soil. i feed it with shcultz plant food 10-15-10 and the plant food in the soil is also 10-15-10. i have 5 cfl lights currently on it all in the 6500K and each with 1600 lumens. the temp is usually around 80 but can get up to near 90 once in a while. i have 2 computer fans installed in the box. and one mini desk fan sucking air out of the top. ph in water is 6.8 to 7.2 and i do mix the plant food with water when i feed it a litter of water mixed wid shultz every 3 days or so i also use the same water to spray the plant when it is in its dark. i had the plant under 24/0 lights and changed it to 16/8 about a week ago. i think its nute burns but dont have any experince can some one please hlep me i hope all the info i juss typed is helpfull to helping me.

most mg soil i see already has nutrients for 3 months or so depending on the one you bought. Then you added plant food into soil and you're feeding it liquid food? Too much! Also growth slows after 80 degrees but that's prolly not ur problem.

The mircle grow is .17-.07-.21 and yes that is a . Infront of the numbers I fig this was too low so I aded the rose food pebles into the soil and wish I didn't but I can't go dig it up now that rose food was 10-15-10 and the schultz I use is the same I add 7 drops to 1 litter of water... Any one help plzz

The mircle grow is .17-.07-.21 and yes that is a . Infront of the numbers I fig this was too low so I aded the rose food pebles into the soil and wish I didn't but I can't go dig it up now that rose food was 10-15-10 and the schultz I use is the same I add 7 drops to 1 litter of water... Any one help plzz

I would run just water through the soil for awhile and see wat happens. Next time you should mix your soil with perlite to make it drain better that can make your feeding more forgiving hard to overwater. But you should work on getting your temps down to 75f your plants will thank you with fast growth.

Also watch your ph and humidity that can cause problems when everything else is perfect.

thnx for the help. how much water should i put in there when do i know if its enough and the soil has drained i decided no more nutes the next couple feeds to see if it changes n e thing