Leaving my post up because it might help someone else. It appears the stuff on my pots is just salt buildup. 
ORIGINAL POST:point_down:
HELP! What is this and what should I do about it?
This is a 7 gallon fabric pot with a feminized lavender germinated on December 26, 2020. I haven’t switched to flower yet because I needed to correct a nitrogen deficiency. I’m also waiting for my 30:1 CBD: THC to catch up. I’m also growing GSC and Chocolope. All have some of this on the pots except the CBD - so far. I’m a beekeeper and thinking of making them a propolis tea, but wanted to check here first. This is the furthest I’ve ever gotten with a grow and now I’m worried I will lose the whole crop!
I have a 5x5 tent with a 6” fan and filter, a small fan, a home-made CO2 generator and a humidifier. Light is a MIXJOY LED Grow Lights GL-4000d/450W Full Spectrum with Samsung LM301 LED Diodes & MeanWell Driver. Using FF nutrients. Another reason my plants are small is I used the wrong nutrients (Grow Big instead of Big Bloom for the 1st few months.)
I took clones from the tops early on and the clones are gorgeous and healthy looking in their 1 gallon plastic pots. I moved them outside now that our days are long enough, but planned to bring the big girls to flower inside.
Thanks in advance for any help.