Thanks @Bonjoyle … I’m sorry for so many questions. I really appreciate your advice!
If my last test run off was only 550, then my next watering should be… what? 1450 ppm? (That is: 1000 + 450)? Or just a straight 450ppm?
I would maintain the 1000. So if you did come back at 550, I would water with nutes at 450-500 ppm and ph it to 6.5.