Can I use River Rocks in my Home Built Hydroponic System?

This Hydroponics Hobbyist wants to know if he can use river rocks in his hydroponic system. Below is where I answer his question along with my opinions about other hydroponic media.



I have used pea gravel just to experiment with but I don't see why river rock wouldn't work just as well but let me explain the purpose of the media. I like the clay balls "Hydroton" because of a few important facts. They hold on to some of the hydroponic solution giving the plant a constant supply if nutrients and water. They also allow the solution to drain away so as to not drown the roots while allowing air to get to the roots. It gives something for the roots to hold on to. It's light weight compared to rocks. Finally I like it because it can be cleaned, sterilized, and used again.


These facts are important also in relation to the type of system you are using. Use of Hydroton in an Ebb and Flow system allows you to have a shorter on and longer off times for the pump. In a drip system it allows the drip zone to be less accurate. If the drip doesn't land directly on the roots it's no big deal because the Hydroton will wick the solution to where it's needed. In other type systems such as DWC, Aeroponic, and NFT this isn't so critical because there will be a constant supply of nutrient and air supplied to the roots.


As you can imagine about the only differences between Hydroton and rocks are the weights and the ability to hold on to some of the solution. In an Ebb and Flow system you will have to flood the system more often and let it run longer to keep the plants from wilting. In a drip system you will get a certain amount of capillary action but it will be slightly more critical to get the nutrient solution to flow over the roots.


Also I'd like to mention brick and lava rocks. They fall somewhere in between the two but if you have to move the plants in any way they will be more likely to damage the roots due to sharp edges. 


Keep in mind the above information and you should be able to use river rocks successfully in just about any system.


I hope this information was useful to you too. If you've had direct experience using river rocks in your hydroponics system please let me know in a post below. Have a great day!