Bubbels, have you even read this thread? Or are you just jumping in at the end? Myself, I have not flushed in a couple of years. Because I can keep the medium in the range I want. But If I feel I need to flush out some of the salts, I just give them a normal mix but more of it. But some people throw off the coco with a huge over load of salts. And keep listening to Canna and all they teach. See Canna is just another greedy corperation looking to sale anything and everything they can. Like where Canna says to use 15 ml/gallon of the A&B, when in fact is to much and causes lots of trouble in itself. Most stains like 4-5 ml/gallon, and the heavy eaters like 6 ml/gallon. This does not mean on some strain, I might not be able to feed it 10 ml/gallon and do well. You need to be flexible. I used nothing but Canna Nutrients when I started in Coco, then changed. Then about 9 months ago, I switched back to try it again, and ran across the same salt build up. I now have been using Cyco brand nutrients and love it. I have not once had my run off going out of wack in the least bit in 3 crops.
One more thing to think about. There are a lot of ways to skin a cat and still get the same pelt. And just because one thing works best for one person. Does not mean it will work best for everyone.
You telling me to do some research before I suggest something. I have done better, and have done it over and over and over.