water + 25% nutrient mix...... This means that every time you water your plants you have to add al least 10% and at most 25% of nutrients....and of course more when they need it..... This will actually leach out the old nutrients better then watering just with plain water and also prevent nutrient lock.... sometimes when you water with plain water (i.e. 0% nutrients) the plants "think" there is a problem with nutrients supply and they try to retain as much nutrients as possible... the stem becomes dark and the leafs look burnt or drooping or .. just unhealthy.... To prevent this from happening you can always add a little bit of nutrients to your water and prevent nutrient lock in a first place..... If you see on this Grow Guide that I talk about plain water, you must change that to water + 25% nutrient mix..... this also applies to the end week of the bloom cycle when for the last week or two you "leach" out the nutrients before harvest.... "leaching" also means adding 10% to 25% of nutrients.....