First timer, please help.

[seed_rar]

This is my first grow ever. Can anyone tell me what is wrong with my plant? She is a Lowryder #1 at 3 weeks old under a air cooled 400w HPS. It just started flowering this week the soil is MG organic potting soil, the fertilizer I have been using is Organic Iguana Juice Grow at 25% strength. She got some chemical burns about a week ago because I fertilized on two consecutive watering spaced 4 days apart, so I gave her some extra water to flush it out and it seemed to stop further damaged.

Two weeks ago the water I was using had a PH of 8, I have now bought a tester and watering with a PH of 6.5. I have three other plants going right now and she is the only one developing this problem.

When she had the chemical burns it started at the bottom but with this new problem it started at the top. It started as faint reddish spot in the middle of one leaf and now seems to be turning brown and spreading to the sides and other top leafs.

Could this be phosphorus deficiency? Because I have been giving low amounts of grow fertilizer with only 1% phosphorus. To me this makes since because she was the first to show sex by about a week, but I don’t know this is my first grow.

 

[trillions of atoms]

feed with a balanced nute, FF makes good stuff. she looks great other than that diff. you would be able to tell if it was nuteburn and its not.... she might need a lil more N too.

 

[seed_rar]

My temps are in the 75-80 range and the humidity is very low.

 

[trillions of atoms]

well low humidity wont do that to a plant so thats not a concern... but balanced nutrients are one. do you have a growshop around you? advancedgardensupply dot com is a good place....

 

[seed_rar]

Yes I do.
Should I go out to the store and buy something with more N, or should I start her on my bloom fert with 436 NPK. Or could it be a phosphorus deficiency?