Sandponics (iAVs)

Sand is a crucial component of the Integrated Aqua-Vegeculture System (iAVS). It serves as both a growing medium for plants and a bio-filter for fish waste. In this section, we will discuss the ideal type of sand to use in an iAVS system and how to prepare it for use.

The ideal filter sand for iAVS has a consistency approximately that of common table salt or of granulated sugar with no powdery fraction. Larger particles can easily be screened out, if necessary. This type of sand provides the best balance between water retention and drainage, which is essential for plant growth. It also allows for efficient filtration of fish waste, which helps maintain water quality.

It is usually relatively easy to find a source of an appropriate grade of sand. However, it is important to choose a source that is free from contaminants such as silt or clay.

When sourcing sand for an iAVS setup, it is important to choose a high-quality filter sand that is free from contaminants such as carbonates, clay, and silt. These contaminants can negatively affect pH levels and nutrient availability within the system, leading to reduced plant growth and microbial activity.

The ideal sand for iAVS should be coarse with a particle size ranging from 0.4mm to 1.2mm. This size range allows for fast drainage and creates large pore spaces that promote atmospheric exchange around the roots. The sand should also be clean and free from organic matter, which can lead to clogging of the biofilter.

One common source of high-quality filter sand is riverbeds or quarries. However, it is important to ensure that the sand has been properly washed and screened before use in an iAVS setup. Some suppliers may also offer pre-washed filter sand specifically for use in aquaponic or hydroponic systems.

It is also important to consider the sustainability of the sand source when sourcing sand for an iAVS setup. Unsustainable mining practices can lead to environmental degradation and habitat destruction. Choosing a supplier that sources their sand responsibly can help to minimize these impacts.

Before using sand in an iAVS system, it must be thoroughly washed and sterilized to remove any impurities or pathogens. To do this, follow these steps:

1. Rinse the sand thoroughly with water to remove any loose debris. 2. Fill a large container with water and add the sand. 3. Stir the sand vigorously to loosen any dirt or debris. 4. Drain off the dirty water and repeat steps 2-3 until the water runs clear. 5. Sterilize the sand by soaking it in boiling water for at least 30 minutes. 6. Drain off the hot water and rinse the sand with cool water.

Once the sand has been washed and sterilized, it is ready to be used in an iAVS system. By following these steps, you can ensure that your sand is free from contaminants and will provide the best possible growing conditions for your plants.

Maintaining the sand in an iAVS system is crucial for the health of both the plants and fish and productivity of the system. Over time, the sand can become compacted or clogged with debris, which can impede water flow and reduce filtration efficiency. To prevent this from happening, it is important to regularly monitor and maintain the sand in your iAVS system.

One way to maintain the sand, if needed, is to periodically stir it up with a rake or small hoe. This will help loosen any compacted areas and prevent debris from accumulating on top of the sand.

Here are some tips for maintaining sand in an iAVS system:

1. Regularly check the sand bed: It is important to regularly check the sand bed for any signs of clogging or compaction. If the sand bed becomes compacted, it can reduce water flow and oxygen exchange, leading to reduced plant growth and microbial activity.

2. Clean out debris: Debris such as dead plant matter or uneaten fish food can accumulate in the sand bed over time, leading to clogging and reduced water flow. It is important to remove any debris from the sand bed regularly.

3. Monitor pH levels: The pH level of the water in an iAVS system can affect nutrient availability and plant growth. It is important to monitor pH levels regularly and adjust them as needed using appropriate buffering agents.

4. Maintain proper water flow: Proper water flow through the sand bed is essential for maintaining optimal conditions for plant growth and microbial activity. Ensure that water is flowing evenly through all parts of the sand bed by checking that all outlets are functioning properly.

5. Replace sand as needed: Over time, sand may become contaminated with organic matter or other contaminants that cannot be removed through regular maintenance. If this occurs, it may be necessary to replace some or all of the sand in the system.

Ideally, 40% by volume consisting of particles 1-2mm, 40% 0.5-1mm, 20% 0.25-0.5mm, and a small amount of particles larger than 2mm.

Sand that contains silt and clay may harbour harmful pathogens or pollutants.

Sand that contains high levels of silt or clay can clog the system and reduce water flow, leading to anaerobic conditions and poor plant growth. It is far better to haul sand from a relatively distant source than it is to wash out even a small percentage of silt/clay from a closer source.

Silt and clay are not good components for filter sand in an Integrated Aqua-Vegeculture System (iAVS). This is because silt and clay particles are much smaller than sand particles, which can lead to clogging of the system. Silt and clay particles can also reduce water flow and oxygenation, leading to anaerobic conditions within the system that can be harmful to plant growth and microbial activity.

To ensure that your filter sand does not contain silt or clay, it is important to test the sand before use. One way to do this is by performing a simple jar test. To perform a jar test, fill a clear jar with water and add a small amount of sand. Shake the jar vigorously for several minutes, then let it sit undisturbed for several hours. If there is a layer of sediment at the bottom of the jar after several hours, this indicates that the sand contains silt or clay particles.

Another way to test for silt and clay is by using a hydrometer. A hydrometer measures the density of liquids, which can be used to determine the particle size distribution of soil or sand samples. To use a hydrometer, mix a small amount of sand with water in a container and let it settle for several hours. Then, insert the hydrometer into the container and measure the density at different depths. The results can be used to calculate the particle size distribution of the sample.