I'll try to make it easy for you:
In coco...Don't flush the plant with straight water. Always check and manage your feed pH. Feed your plant daily. Learn to grow more with less...meaning leave out all the silly additives and additions to your nutrients.
If you think you've given your plants too much N. Take your typical feed (I'll make up numbers for this example) 20-20-20-, and mix up a new feed that is more like 10-20-20. Then, take this new mix and (I'll make up more numbers here), let's say you're growing in a 1 gallon pot...pour a gallon of the new mix (10-20-20) through your pot. This will allow you to essentially reset your coco with the lower N component (10 vs 20). Then sit back, relax and take notes on what you did, why you did it and the results.
Coco is like a chalkboard...you can write on it, erase the words you misspelled and then rewrite them.
Good luck friend.