In hydroponics, not any type of pot, bucket or container can be used. The inner growing pots and outer pots or containers, in which the nutrient solution is stored, must meet certain criteria.
Because in hydroponics the nutrients are dissolved in water in the form of ions, it is important that the pots and containers do not react with the nutrient solution.
Metal containers are not suitable as they react (rust) with and contaminate the nutrient solution.
Some clay pots are not fit either, especially if they are not glazed inside. Brick will also react with the nutrient solution and contaminate it and has an influence on the pH of the solution.
Plastic and glass containers are ideal as they do not react with the nutrient solution.
Since the nutrients are dissolved in water, it is important that no light gets into the containers.
In translucent or transparent containers, algae will appear and this is not good for the plant because the algae also feed on the nutrient solution.
The color of the outer pots is important in regard to possible heating of the content in direct light, whether it is sunlight or artificial light: dark colored plastics absorb light and can become very hot.
The plant might not be able to resist the heat and the nutrient solution will be damaged.
So prefer light colored plastics as their surface reflects light and will not heat up as much as dark colored plastics.
Which pots are the best?
Opaque plastic pots are ideal for hydroponics. They do not react with the nutrient solution, are easy to clean and do not let light through.
Opaque glass containers are suitable too but not as readily available as plastic ones.
You may also use other materials such as a porcelain pot or an old soup tureen, provided that the inside is glazed.
Many different types of plastic jars, bowls and containers are suitable for recycling, provided that they do not let light through.
You can recycle plastic soda bottles that are translucent or transparent for a temporary use, for example for starting cuttings and seeds.
Translucent plastic bottles have the advantage that they are available in different sizes and that they allow to see how high the level of the nutrient solution is and whether there is already root formation.
You can also recycle small plastic pots, like yogurt pots, for smaller and slower growing plants, like cacti.
Make a few holes in the bottom of the pot and put it in a larger pot or pan that contains the nutrient solution.