pics inside: 3 days flowering, new leaves become yellow, humid. prob. (kalashnikova)

Hi guys, my plants are from feminised kalashnikova seeds, i feed them with canna vega A-B 15ml of each per 5L of water and they are in soil. I bought an humidifier but i still cant raise the humidity % more than 30-35. Is it a big problem? The leaves became yellow since i put them in a 32 hours dark period and after swith them to 12/12 under a 1000w hps 3 days ago. I searched a bit on internet but i still dont know what is the problem. Thanks a lot if you can help me!

-Ph around 6 - 6.5
-ppm around 700
-temp. 70F night, 80F day

I have 9 plants and they all look like the first 2 pictures but the 3rd pic is the one that is the most yellow.

If I had to guess I would say that you are lacking N, get a second opinion though because I'm not completely positive. If it ends up being N I would just top dress with a little Bat Guano and it should green your girls right up. It could also be Magnesium (the deficiencies look some what similar). Since you are in the very early stages of flowering you shouldn't have an issue with adding N, if you were mid-flower then it would be a definite now but it shouldn't hurt much if you do it at the start.

As far as figuring out which deficiency it is take a look at where the issue begins, if it starts yellowing at the tips of the leaves and working it's way to the leaves it's N....if your lower leaves are starting to die out and get crispy and the yellowing starts at the bottom and works it's way up it's Magnesium....both are relatively easy fixes.

Nice looking plant.

im having the same issue 2 days into flowering.. its only the top of the plant doing it.. my humidity is the other way as its high like 70% def need a dehumidifier

Completely understand about the Humidity issue, mine sometimes will dip down to 16% if I am due for a watering, most of the time I hover in the 30-35% range with lights out temps of 58-62 and on temps of 71-74, low humidity has never caused me an issue before, I worry about it more in Veg than in flower...I like to keep it low during flower because I have this fear of Mold and Mildew that comes along with higher humidity. Some people use a bucket of water or some wet soil to raise it up, but if you are worried about it you should do it right and pick up a decent humidifier or in the other case a dehuey.