Should I top off with straight water or with nutrients added?

If you are growing in a system that re-uses nutrient solution, like with the ebb and flow method, you may experience a lot of evaporation. You can “top off” or replace this evaporated water by adding a diluted-down 20 – 25% strength solution of nutrient water. Remember that you will have no way of knowing how much of each nutrient (like nitrogen) has actually been used by the plants (and is therefore depleted in the reservoir water.) We recommend completely changing out and replacing all the nutrient solution every 7 – 10 days so you know exactly the ratios you are feeding the plants.