Could you explain the two hydroponic methods?

I researched that there are two methods,the nutrient solution and the sand and gravel method, can you explain each one?

Could you explain the two hydroponic methods?
There are many methods in hydroponics, but I think I know what you are asking about - Hydroponic can get complicated so here are some basic answers to help you get the idea.





The "nutrient solution" method involves suspending a plant in a piece of styrofoam or other similar material and allowing its roots to grow down into a container of water. The water has various fertilizers, ph buffers, etc. in it to make it suitable to sustain plant growth.





The "sand and gravel" method involves using some type of media (like sand or gravel - but there are better choices) in place of the soil in a pot. The pots used can look like regular plastic pots or be mesh baskets. Again a "nutrient solution" (water+) is somehow pumped through these pots. This can be done by different methods such as a constant flow from an overhead pipe where the water is collected under the pots and recycled into the system. There are other methods to provide the water as well.





Here's a neat link to a company that does a "top down" watering system that can recycle or not. I've actually seen this used and the results were impressive.


http://www.hydrostacker.com/photos.html