Just for Kids Hydroponic Question & Answer Page

Do you have a question about your growing system or plants? Submit a question and we'll do our best to give you a speedy answer!

Recently Lee asked:
I’m doing a science project on pH and plants. I would like to know some plants that are alkaline-loving or acid-loving.

D.J.P. from The Growing Edge responded:
Lee, in order for plants to take up minerals, they need a fairly neutral (pH between 6.0-6.5) hydroponic nutrient solution or soil. Some plants will tolerate higher or lower pH levels, but such conditions are not considered ideal. At a lower or higher pH, mineral deficiencies and toxicities can result. Relative neutrality is especially important in media-free growing systems that have the plant's roots in direct contact with the nutrient solution, such as the nutrient film technique (NFT). Plants in media-based systems can tolerate slight fluctuations in pH better since the media acts as a bit of a buffer.

The pH range can be expanded somewhat--especially with media-based hydroponic crops and soil-based crops. Most grass seeds will not tolerate soils below 5.5; most flowers do best between 6.5 and 7; some shrubs, such as azaleas and rhododendrons, do best in slightly acidic soils, from 5.5-6.5. For more information about the specific pH plants desire, I would recommend consulting books that feature profiles of perennial and annual plants.

Good luck with your project!

Recently Dylan asked:
Will plants grow faster/better using distilled or tap water?

D.J.P. from The Growing Edge responsed:
Dylan, the quality of water used for hydroponics or traditional gardening is important. Tap water frequently has elements, such as chlorine, in concentrations that can be damaging to plants. The same applies for well water. However, this is not always the case. Water quality varies from area to area. Also, plants have varying levels of tolerance for certain minerals. Many gardeners never have any problems using tap water.

The only way to be sure would be to have a water quality analysis made. However, these are expensive and unrealistic for most gardeners. You could just try using your water source as a test to see how it effects the plants. One good experiment would be to grow two plants and use your tap water for one plant and feed the other plant with distilled water. Then document the results.

Since most tap water has chlorine in it, there is one step you could do to remove some of that element from the water before you mix your hydroponic nutrient solution or water your plants. Just fill a bucket of water and let it sit in the open for 24 hours or so before using it. The chlorine will quickly evaporate. Stirring the water once or twice a day will help. Placing the bucket in a sunny area also helps evaporate the chlorine.

If you have a small hydroponic system set up or are watering a small number of plants and will only be using a fairly small volume of water, you can't go wrong by using distilled or purified water. Such water has usually been treated with reverse osmosis to remove any existing minerals. Then, trace minerals are usually added to the water to give the water a better taste. When you use distilled or purified water, you can be certain that it doesn't have any unwanted, unmeasured levels of minerals in it.

I hope this helps your understanding of tap water vs. distilled water!