3-9-4 .. Ran straight FFOF for 6 weeks prior and everything was great. Flipped to flower and added the recommended amount of flower nutes (Dr. Earth flower girl) and it was fine for about 2 weeks and then this stuff started to slowly appear. Reckon I should just flush the Hell out of it? I wont harvest much, but maybe it'll improve the taste?
I wouldn't flush from what I see.
Your watering habits should be ruled out as a problem.
How often do you water and how much do you use each time.
If you are keeping the soil to wet (easy to do in a 7 gallon pot) it creates a low soil PH resulting in nutrient lock out.
If that is happening flushing is the last thing you would want to do.
Why flush anyway?
If I read correctly you only fed it the organic DR Earth and cal/mag.
Flushing or leaching is done to remove a salt build up from a soil.
There is no reason for there to be a salt build up in your soil IMO.
What kind of water are you using? Tap? RO?
What are the ppms or E/C of the water you are using?