Pea gravel
Also known as: Pea stone, River gravel, Aquarium gravel (smooth varieties)
Properties
| pH effect | varies by source |
|---|---|
| Water retention | very low |
| Drainage | excellent |
| Oxygen to roots | high |
| Bacterial surface area | moderate |
| Reusability | very high (essentially permanent) |
| Cost tier | low |
| Weight | very heavy |
How it affects the system
- pH depends entirely on stone composition: limestone-based gravel raises pH (vinegar test fizzes), silica/quartz/basalt gravel is inert
- Vinegar test BEFORE filling a system: drop white vinegar on a few stones; bubbling means calcium carbonate is present and the gravel will buffer pH upward
- Very heavy: a 4x8ft gravel media bed needs a solid stand and may need reinforced flooring
- Smooth surface compared to lava or clay pebbles: less bacterial colonization, biofilter capacity is moderate not high
System compatibility
Works well in:
- media bed (ebb and flow)
Avoid in:
- NFT channels
- deep water culture (rafts)
- drip
- wicking bed
Care notes
Often the cheapest viable media-bed substrate in a given region. Always test for inertness before committing a system to it: a few drops of white vinegar (a weak acid) that make the stones fizz reveal calcium carbonate, which will buffer system pH upward, while silica, quartz or basalt gravel stays inert. Some commercial aquaponics farms use crushed basalt or river gravel for the cost advantage, accepting the lower biofilter performance.
Crops that work in pea gravel
1 edible crop in the catalog list this medium as compatible.
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