Blue Dream is yellowing 21 days into flowering

Dude, in promix you need to be feeding at least every other watering....if not 2 out of every three. I always water 'til I get run-off and feed every watering until the last two weeks of flowering. You're starving the shit outta those girls.

Before you add 1500 ppm do you know what the ppms are in the pot before you add the nutes again. Like what was run off last watering ph and ppm.

I am also doing blue dream nitrogen deficiency seems to be a common obstacle with this strain I always run into yellowing leafs with it guess it demands a higher nitrogen level than most strains, be careful of course because It's so easy to burn your plants when it comes to nitrogen. Best luck