With normal use, some nutrients are depleted from the nutrient solution over time. Others may become concentrated as they go unused and water is withdrawn. Water is added to the solution as it is used, but every two to three weeks the nutrient solution needs to be replaced.
The use of a solution containing all 13 essential nutrients is the most important factor in the health of the hydroponic system. Most general fertilizers do not contain all necessary micro-nutrients, so the use of a nutrient formula specifically formulated for hydroponic use is recommended.
Gather supplies to make the transition swift. Try to limit system downtime.
Turn off the water pump and disconnect the power.
Drain the spent nutrient solution from the reservoir into a bucket for use elsewhere. Spent nutrients can be used as a fertilizer for other garden plants.
Inspect the nutrient reservoir for signs of algae growth or other microbial problems. If algae or other growth is present, continue changing the nutrients, then consult your nutrient supplier about the use of probiotics to control these problems.
Refill the nutrient reservoir with the prescribed amount of water.
Add the measured nutrient solution to the water, mixing thoroughly. If using a two-part nutrient solution, be sure to mix thoroughly after each addition.
Adjust the pH of the solution to the desired level for your plants and growing media. The pH should be between 5 and 6.
Replace the lid on the reservoir tank and restart the pump.