Yellowing leaves - Lock-up Wat-up?

[Tatva-2]

Plant is really healthy and started to produce hairs (pre-flowering?)

Lowest leaves starting to turn yellow:
Normal as it flowers? Lack of some element? Lock-up? Wat-up???

1st time in a long time grow. Any help is great.

 

[Cannabinoid]

What is your pH? Indoor or outdoor? Lower leaves yellowing or bloching is signs of deficiencies. Looks like a phosphorous deficiency to me (that is if your pH is stable).

 

[Tatva-2]

OK thanks for that.

Have some problem getting gear for growing as this country in Asia is pretty strict if I get caught.

Tried to find a ph meter but no luck so far. Ordered one on the internet but the company billed me but did not post the meter (jerks).

Any how, Cheers and thanks for the help