Do I flush once, and then start the Nutrients righ...

It seems that every week you are trying to solve a different deficiency or burn / excess. For now, flush and don't feed again, let the plant recover for at least a week. Plucking the burnt leaves or not does not matter, if the burn is serious they will die, else they will survive, regardless of you plucking them or not. Now, manganese deficiency? Really? That's almost impossible, what you probably are seeing weekly is minor / secondary nutrient lockout, due to Macro nutrients excess. Get an EC/PPM meter, that will help you stop guessing how much is too much; feed every 5 to 7 days and only start when you notice the begining stages of deficiency. With good soil, you don't need to feed on veg stage. If your tap water EC/PPM is below 0.4EC/200PPM you need some cal/mag, else there's enough in the water. As for feeding strength, I would start in flower with 1.2EC/600PPM and ramp it up as needed up to 1.4 to 1.8EC/700 to 900 PPM, depending on how hungry the particular strain is.

hello. you mean the watering=? I water my plants and the other day i give them nutrients. the soils should never be dry if they get nutes. you can also water them and dirct after taht feed them. Btw your plants dont look very healthy. If you tanke some pictures (holeplant / leaves only etc) without your growing light we can diagnose what she got.If I would be you i would stop nutes until you know what your lady has.....here is a helpful site until then. https://www.growweedeasy.com/cannabis-symptoms-pictures.