While THG answered the bigger question, I will try to elaborate a little and answer one specific question you have, which is what do you do now.
First, "organics" is ALL about microorganisms in the soil. We say "microbes", "microherd", "beneficials", or "beneficial microbes". When someone says the soil feeds the plants, what they mean is that there are millions off microbes in the soil that break down the raw elements and then literally take the "chelated" nutrients that they (the microbes) have made to the roots off the plants and trade them for carbohydrates that the plants produce.
You can use organic soil, which is soil that has lots of raw materials and loads of microbes to grow your plants, and only give them water, and the microbes will feed the plants until they either, are no longer able to keep up with the needs of the plant, run out of raw materials to break down to give to the plants, or something happens that harms the microbe herd and prevents them ffrom feeding the plants. At that point you can either add more raw materials and/or microbes, or you can feed with nutrient tea, which is an organic, liquefied fform of both raw and chelated materials that can be used by the microbes to feed the plants, or you can switch to using synthetic nutrients and allow the microbe herd to die off.
Some people here with start with organic soil and allow that to feed their plants until its nutrient store is exhausted, then they will switch over to using synthetic nutrients ffor the rest of the grow. With total organic grows, many people will try to use or make "super soils" or amended organic soils. These are organic soils that have extra raw materials added to their mix and then have beneficial microbes added or water with "microbe tea". The microbes then have much more available materials to pull from for making food for the plants.
Now you can use unamended organic soil for growing in but never incorporate the use of microbes. Instead you would begin feeding right away with synthetic nutrients, which will kill off the microbes over time. How quickly the microbes die off depends on the synthetic nutes, the amount used and the pH that the soil is kept at.
Now to confuse you a bit more; you can use synthetic medium to grow in and still use organic nutrients to feed with as long as the medium that you use will support the microbes that are important to the "chelation" process. For example, you would have little problem using coco coir as you grow medium and then either add some raw material amendments to that, and/or feed with organic nutrient teas. This is because the microbes would be able to stay and survive within the coco coir.
However, as another example; you wouldn't have a lot of luck using "hydroton", or other very coarse aggregates for a grow medium with organics, either in hydro or in soilless.
Now to your main question of what should you do now. For those people who grow with synthetic nutrients, I personally recommend that you flush about halfway through the grow just to prevent buildup. Yes, flushing, if done right will strip out nearly every bit of nutrients and chemicals within the medium/soil. That doesn't hurt a single thing (unless you are using organics. Never flush organics unless there is a majorly serious problem). When growing with synthetic nutrients, you can flush and strip out every bit of nutrients in the medium, and then turn around the next day(or 3 days later) and go right back to feeding, and they will not miss a beat.
Even though you are growing in organic medium, since you have been using synthetic nutrients, you have most likely wiped out the microbes in the soil, so you are officially growing synthetic. You can just continue going like you have been, and just remember that
you are doing the feeding of the plants (not the soil).
Whether to flush or not is entirely up to you. If you have been using Fox Farm nutrients from the beginning, I would highly recommend that you flush them one time so that you don't run into toxic buildup when you get to the 7th week of flower (when it is so difficult to bring them back from the damage). To me it is worth the one time flush mid way to keep that from happening. being in organic soil, flushing is going to be a bit messy as it is going to produce a significant amount of mud drain. If that is going to be a problem for you to do that at this point then you can go on without flushing and hopefully not get toxicity. As I said, the choice is yours. I hope this all makes sense and helps
