Why you need a substrate for Hydroponics
While you are using water as your primary source of nutrients, there is still a need for a substrate where the seed is placed and the plant extends from. Your plants need stability and still be able to breathe and have space for their roots. There are many commonly used substrate for Hydroponics, and following article, I will go over the most useful ones.
Which substrate you should use
One of the most used substrates is rock wool. While it provides great water absorption, it is quite thick when dry. This is why I recommend always soaking it a good while in water before using it in you Hydroponic System. The great thing about these rock wool cubes is that you can go from seed to mature plant in it.
Though, depending on the net pots you are using, you would want to cover the outside of the cube with some other substrate, such as foamed clay pebbles, coco chips or small lava rocks. It is important that the substrate has enough space for the roots and oxygen to get to the plant but still block out any light from reaching the roots. Ideally, it is porous and allows for air flow.
How to prevent algae in Hydroponic substrates
Algae are one of the worst things that can happen to your reservoir and root systems, and they need light to grow. This is why you want to cover the outside of your rock wool cubes with another substrate, blocks the light from reaching the roots. There are different opinions about this, but I like to have a thin layer above the rock wool as well, since I have seen these things completely covered in algae. This is not good for the plant, since it is centered around the cube.
In general, where there is no light, there’re no algae, so to prevent algae, blocking light is the best way. This is why you need to use non-transparent materials for everything. NFT channels, tubes and pipes, your reservoir, everything. You don’t want any light to reach the water or the roots at any point, as that risks algae in your Hydroponic System.
What you need to watch out for
As mentioned above, one of the most important things to watch out for when choosing a substrate is that it can properly cover the opening for the plant pot, so that no light can reach the roots and the water. In addition, you want to make sure the roots can still reach the water, otherwise they will have no way of getting the required nutrients!
Learn more about the advantages of Hydroponic growing here!