Is this Magnesium or Nitrogen Deficincy? with pics

Im in day 22 of Flowering and the bottom leaves of my plant are turning light green to yellow and eventually falling off.
Here is one of the lower fan leaves on my plant. This happened last time I grew and the whole plant eventually died.
Please help!

From the looks of things its not a nitrogen problem as you would be able to tell throughout the whole plant....I would lean towards MG. but how is the ph lvl of the soil??

lonleysmoka said:

From the looks of things its not a nitrogen problem as you would be able to tell throughout the whole plant....I would lean towards MG. but how is the ph lvl of the soil??

Click to expand...

I dont know, How do you measure the ph?

^ Cheep Ph Meeter. Go to lowes or home depot, even walmart has them i think

okay thanks, What should be the PH of the water that I give my plants?

bump...................

ph of around 6 is good