No need to starve your plants for the last week. Just give them 1/4 to 1/2 what you usually do.
yes wash your pebbles. Soak in pHed water and a little bleach.
Thanks, Myke. Being cautious, I've never given the plants more than 1/2 the "book" nute strength - and mostly around 1/3. Never spotted a deficiency - in fact, I got a tiny bit of tip burn when I added a small dose of FoxFarms Big Bloom to the res. I used it once more, applied directly to the plants - and got some REAL greening & swelling of the buds.
Will soak overnight as you suggested once this harvest is done. Learning a lot!!