Mysterious Leaf Necrosis - Please Help

[chizarium]

Hi all, I've been growing for about two years and I have a plant problem right now that I've never seen before.

I recently purchased and setup a Secret Jardin grow tent to flower my two small plants in. From what I read online this is a high quality tent that does NOT release those plant-killing fumes that many others have experienced with HydroHut tents and some others.

About 3-5 days after transplanting my two small plants and putting them in the tent for flowering I began to notice leaves turning different colors, shriveling up and dying and necrotic-looking. I already grew this strain a few times in a different grow area and di not have these problems, and everything I'm doing now is the same as before.

I took pictures of a few of the leaves that have problems. I also included a picture of the top of the plant to show you that overall the plant looks very healthy there are just random leaves dying for no good reason. I inspected the plants carefully and cannot find any pests. The amount of leaves having this problem seems to be increasing and not getting better.

Here are the details of my grow:

What type of medium; soil or hydro?
- Soil

What brand and type of soil?
-Pro-Mix soilless mix

Indoors or outdoors?
- Indoors

What strain?
- Not sure

How old are the plants?
- Started flowering ~10 days ago, vegged for 4 weeks before that

What type of lights and how many watts?
- two plants under two 150-watt HPS lights

How far from the lights?
- far enough that the tops do not burn, at least 12-16"

What, how much and when was it fed? NPK?
- they are fed a 3-4-7 chem mix with calcium (the same nutrients that previously provided me with great results)

What is the medium/runoff pH?
- dont know pH

What are the temps and humidity in the room?
- with lights on about 85 degrees, about 73 degrees with lights off - humidity averages 50-60%

What size pots?
- 2 gallon

Any bugs? Look real close.
- none that I can see

Any other pertinent info?
- Growing in a Secret Jardin DR80 grow tent with reflective mylar-type interior lining.

Thanks for any help!

[C12]

possible phosphorous deficiency? i have something similar on a few leaves and thats what i think it is.

[fondacox]

i am having the same problem. I have tried everything.

The only thing left to believe is the plastic is killing them.

I am wondering if I wash it with tsp if it would be better?

Does anyone have any ideas?

[Ganja Guerrilla]

phosphorus def

check your ph runoff to make certain the ferts are being made available...when were they last fed?

[chizarium]

i think you're right it definitely looks like phosphorus deficiency - but i really dont think im depriving them of P b/c im using the same nutrients i always do, i think you're right about the pH, i have these plants in soil whats the best way for me to test the pH of it?

i feed/water them every 2 or 3 days (whenever the top .5" of the soil gets dry)

ALSO i noticed something else happening today - the pistils on some of the buds on the BOTTOM half of the plants look like they're shriveling and the plants are only in their 3rd week of flowering, and not in the good way like they're ripe, in a bad way like they're being burned or something

does this ever happen with a P deficieny also or do i have multiple problems?

thanks for all your help!