Yellow then brown leaves twist & curling up (Beginner)

1st Time attempting to grow, complete beginner, and I just don't understand what is going on with my little ones. Yellowing starts at the very tip of the leaves, and will eventually turn a light brown and crispy, one plant tips curl upward, while the other plant leaves twist. The stems are mostly green around the leaves but a bit lower down is a purple/red color.

**Pictures**
http://imageshack.us/photo/my-images/5/img20130503185340.jpg/
http://imageshack.us/photo/my-images/541/img20130503185321.jpg/

Fox Farm Ocean forest soil
Sprouted, then planted on March 31st little more then 4 weeks old and barely 3 inches tall. Seems pretty slow growth to me, but I'm a beginner.
Got 2 plants going under a starter 25w T5 light, currently 4 inches from light, planning to go to 150w HPS light with 16,000 lumens when it got bigger.
Growing indoor in your average closet (I'll get measurements if requested)
I wait to water when top soil is completely dry and the leaves begin to droop a little, with the current size of the pots (3in tall, 3in wide) it comes around every 2 days.
I started the PH around 6.5 but after the yellowing the leaves I lowered it a little to 6.0 I use regualar tap water but I let it sit for 24 hours with out a top/cap before use. I have used nutes only once, Fox Farm Grow Big, that was before leaves turned yellow fearing of nute burns, the one time I used nutes when watering I used a 1/2 teaspoon a gallon of water, also added 3 drops of super thrive, checked and adjusted PH after adding nutes.

Any help would be GREATLY appreciate, also please let me know if I need to give any more information. Thank you for your time and help I appreciate it.

Is that plant even in the pot!?

Yes it is in the pot and planted in the center, its not leaning or anything, I just took the picture at a weird angle.

when you said your ph was at 6.5 then u when to 6.0 i think thats what started your problem idk i could be wrong but i use fox farm ocean forest too and it already has a ph adjuster in the soil at around 6.2-6.5 and making your ph at 6.0 could cause issues cause i make sure my ph is always at 6.3-6.5 and dont have any issues...Good luck

420 happends said:

when you said your ph was at 6.5 then u when to 6.0 i think thats what started your problem idk i could be wrong but i use fox farm ocean forest too and it already has a ph adjuster in the soil at around 6.2-6.5 and making your ph at 6.0 could cause issues cause i make sure my ph is always at 6.3-6.5 and dont have any issues...Good luck

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fox farms ocean forest does not always come at a ph 6.2-6.5
Not saying that it doesn't at all but I have had multiple batches around 5.6-5.8

I lowered the PH from 6.5 to 6.0 after they started to yellow.

Is there a ph adjuster in the soil?

like i said "i could be wrong" wasnt too sure any way.

and my batch of fox farm i tested and it was just under 6.3 soo some do and some dont i still wouldnt have my ph at 6.0 i do better at 6.3 ish.

Friedrice said:

Is there a ph adjuster in the soil?

Click to expand...

No there is no adjuster in the soil, I just test the PH using a liquid solution included in the PH kit before watering.