Water makes up to 90% of the plant mass grown. Furthermore, most hydroponic setups recirculate water in a closed-loop system, making the quality of what we “feed” the plants a crucial factor in the growing operation’s success.
Critical Parameters In Determining Water Quality
Plants in water systems only are sensitive to DWC and NFT while plants in substrate like coir and perlite are more forgiving. The water’s pH directly affects the nutrient uptake by the plant and therefore needs to be carefully measured and controlled.
pH adjustment by adding an acid or a base to the water should be made as the last step before the water goes to the plants.
Electrical Conductivity indicates the salts and dissolved solids in the water. The purer the water, the fewer ions it will have available, the lower the EC. However, determining which salts are responsible for that reading and in-depth lab analysis is required.
This and the water turbidity will determine the filtration system used (RO, Ultrafiltration, aeration, settling tanks…) and dictate the fertilizer recipe that will work best for these parameters.
Too warm, and the dissolved oxygen will come out of the solution, and pathogens might proliferate. Too cold, and it will harm root development and nutrient intake.
Several methods exist to mitigate this issue which increases a lot in closed-loop irrigations and where shallow films (NFT…) of water are exposed to high-temperature environments.
City water sources have chlorine added to control any pathogens that might get into the water system. Chlorine can be harmful to plant development and will also affect the root system’s microbiome and/or eliminate many beneficial organic elements in the water.
The best way to remove Chlorine/Chloramine is to aerate the water for 24hrs before use or passing it through a charcoal filter. Another option would be adding Potassium metabisulfite, commonly used by brewers, to remove both Chlorine and Chloramine.
Keep in mind a reverse osmosis system removes all the dissolved minerals in the water in addition to the pathogens. Also, a water softener will add more salt to the system due to how it works.
A healthy water system will produce a more nutritional yield with fesswer issues and more uniformity. With the ever-increasing water scarcity issues, optimizing your water usage by keeping it within optimal operating parameters will also reduce waste and maximize its benefits and use.