There are a variety of ways to operate your system in regards to getting nutrients to the plants. Depending on your scale, functionality, and needs there may be one that is a better fit for you than another: wick, water culture, ebb and flow (flood and drain), drip (recover or non-recover), NFT (Nutrient Film Technique) and aeroponic. For more information on each of these methods check out the link on the image - thanks to simplyhydro.com. The image pictured in of a drip system with recovery.
What we want to consider though, regardless of the process for nutrient solution, is what happens to the nutrients in the solution on their journey from solution to plant.
Most pH's will need to be lowered slightly in hydroponics, based on average water types, to the plant favorite range - 5.8 to 6.2. One of the often overlooked pieces to understanding pH is the media used. Various media types can cause pH to fluctuate up and down - even to dangerous levels. In order to counteract this and better understand what you are working with it's best to test, not only your water, but also the media. Using distilled water, naturally at a neutral pH of 7, submerge the media in the water overnight. Come back in the morning and check the pH level again. This will allow you realize the effect of the media on your pH level.
Moving on, the next nutrient solution piece, often the most considered, is the additive stage. There are various additives that will help create a consistent blend of nutrients in your water. The key nutrients for nearly every plant are contained in these: nitrogen, phosphorus and potassium. With today's technology additives are relatively intuitive and easy to acquire. The key is understanding when to refresh your solution. In order to most accurately estimate refresh times it's important to monitor and control all of the variable involved in your system. Everything from EC to pH must be considered. Over time water will be removed from the system and it will alter the variable that create optimal growth. This means that actively monitoring all variables will give you the best snap shot of system performance and premium condition needs.
Always try to remember the nutrient solutions sequences.
3. Monitoring and Controlling
4. Change Initiation
North Carolina Department of Agriculture and Consumer Services