Possible magnesium deficency

So new update, I've got 2 more lights. My plants have a deficiency (more then likely magnesium). I clipped some of the leaf. This deficiency also seems to be apparent in 2 of the plants. It would be much appreciated if i could get a diagnosis and a solution for what I need. I plan to getting some nutrients, suggestions appreciated. Stay green

Also note I took them off their cycle for a few seconds for it is why i suspect the reason for the small one drooping.

I've got further info in my journal and discussion.
https://www.rollitup.org/grow-journal-discussion/403562-closet-cfl-first-attempt.html
https://www.rollitup.org/grow-journals/403580-closet-cfl-first-attempt.html

Looks like Phosphorus deficiency. Here's an example of a P-deficient leaf:


View attachment 1413842

Also i just potted them in a new pot. What would be good to get for phosphorus deficiency.

Its pretty rare that plants in the first stages of veg would develop phosphorous deficiencies purely based on the fact that it might be lacking in the soil. Phosphorous deficiencies generally develop because the roots are stressed because of some other reason, therefore stop uptaking certain macro and micronutrients which leads to what looks like a P deficiency.

Probably would help if you could fill us in on what you have done so far. i.e which potting mix did you buy, what fans are you using, how much light, where are you extracting the air to, how old is the plant, what are the temperature variations in your closet, what is the humidity as well. That sort of thing.

I fan them 4-5 times a times a week with the window up to get some fresh air for about 20 minute intervals, followed by a rotating heater. They're in their third week, i've got 3 5000-5500 k cfls, a 65 watt cfl, and a 47 I believe. I haven't really set anything up to extract the air. the temp remains 68-73. unsure of the humidity I keep a pot with water in it on my radiator to humidify the room. The plant itself is in it's 3rd week of veg. I just gave it some nutes this week I believe off the top of my head ( I'll have to find the information later) the values were 9-3-3? I'd have to get back on the potting mix. That's the basic gist. my PH levels are 7. The origin of the plants are unknown. I hope this helps in a diagnosis. I plan to try to treat it for a magnesium deficiency if anything. At some point today, I also plan to get some more nutes / micronutrients. Any advice would be much appreciated before I go out and get anything.