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Unit 2 Part (C). Experiment 3 Comparing Growing Media  Many types of growing media have been used for hydroponics and there may be many more that have never been tried. Some of the common types of media that are used in hydroponics are: Perlite - a volcanic rock of gray obsidian, that has been heated to 1500 degrees F in a kiln and expanded. It is a lightweight porous material that can "wick" water from a bottom container of water. Ceramic grow rock - a clay material also called Geolite, which is often used for aquaculture because the porous material is a good media for growing bacteria to clean water. It does not break down. Rockwool - a material made from rock spun into a fiber like material. A phenol-based resin is added as a binder. Rockwool also tends to increase the pH of the water. Pea gravel - this media is just simple gravel but has been graded for size and shape. It is not a porous media so it does not wick water from below and must be used in a system that provides aeration for the water. It can be used to grow bacteria as well as plants. Different media provide different positive and negative affects for a hydroponic system. Also, some are more available or cheaper than others are are. Some have an environmental impact greater than others do, in the ways they are gathered or manufactured. If you can find perlite, it is probably the best media you can use for a home system. Perlite is forgiving for the beginner because it will retain water for three or four days if you forget to water your system. If Perlite is not available, gravel is a good second choice because it will allow for a once a day watering and does not break down. In this experiment you can compare plant growth behavior in 4 types of growing media. 1. Prepare four growing pots in a water container. 2. Fill each with a different media such as gravel, perlite, sand, etc. 3. Plant a bean or pea seed about 1 inch below the surface of the media in each of the four pots. 4. Place the pots sunlight or sufficient artificial light and record signs of growth for each media every day. DATA RECORD SHEET Inspect, observe and record data about the plant's condition. Once the plant has germinated and broken through the growing media, include an illustration of its appearance and begin recording on Day 1.
Revised: 1 May 2016 | ||||