Pebbles
Origin
Pebbles are small stones, sometimes graded for size as in pea gravel.
Pebbles are a natural product, requiring no energy for manufacture, but some energy in transport and in crushing at a quarry.
Characteristics
Pebbles are very heavy and require strong and usually floor mounted growers.
Since pebbles are not manufactured there are no binders, and usually very little contamination.
Pebbles do not wick water up through pores so the media is not usually very good in propagation.
Pebbles provide a natural though limited habitat for microbes, and so they can be used
for aquaculture hydroponic systems. Since there is very little surface area for microbes in themedia,
an aquaculture filter will require more surface area that other types of media.
Durability
Pebbles are perhaps the most durable of all hydroponic media.
They are easily sterlized at high heat, or in the sun. Once a good pebble
media hydroponic system is established, there are no more media problems.
Pebbles also are inert, and probably provide a healthy human environment because they produce very little
dust.
Environment
Pebbles can be recycled to the environment, or recycled in the
hydroponic system with very little energy. However, pebbles may be gathered from streambeds
which can be a serious environmental problem. The pebbles in streams act as a
natural water filter, fish habitat and perhaps provide for stable waterways.
Rock can also be gathered, and perhaps crushed rock can be used
If an environmentally friendly source for pebbles can be found, it is
probably the best media for reduced environmental impact.
It is imporant to note that pebble beds, with nutrient water, also act
as a near perfect passive solar energy collector. That is, they will gather heat
during the day, keeping the room cool, and then release that heat at night, keeping the
room warm. This makes pebbles a natural media to use for passive solar systems such as attached greenhouses and
solar greenhouse structures.
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