Need some help please

Hey gang i am having a few problems with my leaves...Does anyone think that the cause of this is because the roots arent getting enough oxygen to absorb all the water when im watering it?? I am using regular pots...I using 3 gallon pots with maricle grow soil and im using Bloombastic for the final weeks of flowering...

Anyone out there that might know?

it's probably the miracle grow. get Foxfarm or an ogranic mixture. but to answer: maybe N def? or P?

How to i check the ph and shit and maybe correct it?

looks like a lockout of nutes, body. do you check the ph of the water you give?

how close to harvest are you, you said something about last few weeks of flower. if your in the final stretch dont even worry about it, alot of times leaves will yellow towards the end of the grow.

To thcsexy: I have 2 plants that almost ready to harvest and i have 3 that r about 3 weeks flower and 1 plant of my 3 plants r starting to get this problem to...so idk...but i just water when the first couple inches is dry..
To mat: Yeah my 2 plants r almost ready to come down id say in 10 days...but i dont think its because the end of the grow for them i think its something with the roots or something idk..BUT i do have think gnat things swirling in the soil and shit so who knows i just know that 1 of my younger plants is getting this on a couple of there leaves now as well.

Here's the grow