How each medium affects the system
Aeroponic (no medium, misted roots)
Also known as: Aeroponics, High-pressure aeroponics, Low-pressure aeroponics
- Highest possible root oxygenation: roots are continuously misted then exposed to humid air, producing fastest growth rates of any hydroponic method when run correctly
- Pump failure or clogged nozzles kill plants in minutes to hours: no buffer reservoir, no medium moisture
- Calibration-sensitive: droplet size 30-100 microns is the standard for high-pressure aeroponics; outside that range performance falls off
- Difficult retrofit: most hobbyist aeroponic setups are purpose-built tower or chamber systems, not adapted from other hydroponic methods
Currently not a supported system in the garden planner because it sits outside the dwc/nft/vertical/drip/media-bed/wicking/soil-bed enum. Listed here as reference material; future planner work may add aeroponic as a system option. Realistic for advanced hobbyists with a high-pressure pump, accumulator tank, and timer-controlled solenoids.
Suitable systems: aeroponic.
Avoid in: media-bed, nft, dwc, drip, wicking, soil-bed.
Expanded clay pebbles
Also known as: LECA, Hydroton, Clay balls, Expanded clay aggregate, ECA
- Excellent biofiltration substrate for aquaponics: high porous surface area colonized by nitrifying bacteria, reduces or eliminates need for a separate biofilter
- Light enough that a 4x8ft media bed remains movable when dry
- Inert: does not buffer pH; system pH will drift toward source water natural value
- Floats when first wet; pre-soak for 24 hours before stocking plants or it will displace water from the bed
- Cheap-grade products release clay dust on first fill; rinse aggressively until water runs clear
Standard hydroponics/aquaponics workhorse media for any system where pebbles are appropriate. Reusable for years; rinse between crops to remove root debris. Sterilize between sick-plant cycles with a bleach soak (1:9 bleach:water) followed by triple rinse and re-pH.
Suitable systems: media-bed, drip, wicking.
Avoid in: nft, dwc.
Coco coir
Also known as: Coconut coir, Coco peat, Cocopeat
- Natural pH typically 5.5-6.5; well within most crop targets without adjustment
- High cation-exchange capacity: binds and slowly releases calcium and magnesium, can mask Ca/Mg deficiency until it depletes
- Untreated/cheap coir is salt-laden from saltwater processing; buy buffered/washed grade or rinse with calcium-magnesium solution before use
- Breaks down over 2-3 cycles; eventually compacts and loses drainage
Frequently mixed with perlite (50/50 or 70/30) for hydroponic dutch-bucket systems to add drainage. Pure coir works well for hand-watered or drip-irrigated dutch buckets. Buy buffered coir (RHP-certified) or pre-rinse cheap coir with CalMag solution before planting.
Suitable systems: drip, dutch-bucket, wicking, soil-bed.
Avoid in: nft, dwc, media-bed.
Lava rock
Also known as: Scoria, Volcanic rock
- Best-in-class biofilter substrate: extremely porous, more bacterial surface area per liter than clay pebbles
- Heavy: a 4x8ft media bed of lava rock weighs significantly more than clay pebbles when wet; build the stand accordingly
- Sharp edges: handle with gloves; can damage soft roots of seedlings on initial transplant
- Cheap source for biofilter media if available locally; check vinegar test (no fizzing = inert)
Source matters: red and black scoria from landscape suppliers is fine; some agricultural lava products are dust-heavy and need rinsing. The sharp edges that damage soft roots also lock plants in place once rooted, useful for tall fruiting crops that would otherwise need staking.
Suitable systems: media-bed.
Avoid in: nft, dwc, drip, wicking.
Net pot, no medium
Also known as: Bare-root, Net cup, Net pot with no growing medium
- Roots dangle directly in nutrient solution (DWC) or sit in shallow nutrient film (NFT); medium plays no role
- Plant support is purely mechanical: the net pot collar holds the stem; transplant timing matters because root mass develops below the pot, not within it
- Pump failure or solution starvation kills plants within hours: roots dry out fast with no medium reservoir
- Easiest cleanup between cycles: rinse net pots and reuse indefinitely
The simplest possible approach for DWC and NFT. Plants are typically started in a small rockwool or coco-fiber starter plug then transplanted into a net pot once roots emerge from the bottom of the plug. After transplant the plug stays as a tiny support cube but the bulk of the root system is bare-root in solution.
Suitable systems: dwc, nft.
Avoid in: media-bed, drip, wicking, soil-bed.
Pea gravel
Also known as: Pea stone, River gravel, Aquarium gravel (smooth varieties)
- 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
Cheapest viable media bed substrate in many regions. Always test for inertness before committing a system to it. Some commercial aquaponics farms use crushed basalt or river gravel exclusively for the cost advantage, accepting the lower biofilter performance.
Suitable systems: media-bed.
Avoid in: nft, dwc, drip, wicking.
Perlite
Also known as: Expanded volcanic glass
- Almost always used in a mix, not pure: pure perlite holds no water and dries out too fast for most crops
- pH neutral and inert; does not buffer or affect water chemistry
- Smooth glass surface: poor bacterial colonization compared to porous media
- Compacts and degrades over time, eventually creates fines that clog drip emitters
Wet perlite before adding to a system or you will breathe the dust. Wear a mask when handling dry. Standard component in coir-perlite hydroponic mixes; rarely used alone except in some dutch-bucket setups for fast-draining crops like strawberries.
Suitable systems: drip, dutch-bucket, wicking.
Avoid in: nft, dwc, media-bed.
Pumice
Also known as: Volcanic pumice, Horticultural pumice
- Lighter than lava rock with similar bacterial surface area: a good compromise medium for media beds where weight matters
- Less sharp than lava rock; safer for handling and on soft roots
- Regional availability: widely sold in volcanic regions (Pacific Northwest, Italy, Japan, New Zealand), harder to source elsewhere
- Mixed sizes available: smaller grades work for drip systems, larger for media beds
Underused medium that fills a niche between clay pebbles (expensive, manufactured) and lava rock (heavy, sharp). Where available locally, often cheaper than clay pebbles with better biofilter performance.
Suitable systems: media-bed, drip, dutch-bucket.
Avoid in: nft, dwc.
Rockwool
Also known as: Mineral wool, Stonewool, Grodan
- Manufactured pH around 7.0-7.8; must be pre-soaked in pH 5.5 water (mild nutrient solution) for 24 hours before sowing
- Sterile by nature: no microbial buffering, so beginner-friendly but unsuited to aquaponics which needs the biology
- Compresses over time as roots fill the cube; one-shot transplant medium
- Holds excess water near stem base: risk of damping-off in seedlings, root rot in mature plants if oversaturated
Handle with gloves and a dust mask. Standard commercial-hydroponics starter cube. Most starts from seed begin in a small 1.5-inch rockwool cube, then transplant into a larger system. Not recommended for aquaponics: the biology that defines aquaponics has nothing to colonize on sterile mineral fiber.
Suitable systems: nft, dwc, drip, flood-and-drain.
Avoid in: media-bed, wicking, soil-bed.
Soil-based mix
Also known as: Potting soil, Garden soil, Compost-amended mix, Container mix
- Brings its own biology: any aquaponics or hydroponics system that uses soil ceases to be aquaponics or hydroponics in the strict sense
- pH depends on source: peat-based mixes run acidic (5.5-6.0), compost-heavy mixes run neutral to slightly alkaline
- Holds nutrients between waterings: reduces the frequency and precision required for nutrient management compared to soilless systems
- Pest and pathogen vectors: introducing field soil into a clean indoor setup is the most common route for fungus gnat and root-knot nematode infestations
Used in wicking-bed systems and traditional in-ground or raised-bed gardens. The site lists soil-bed as a system option because many readers grow some crops in soil alongside their hydroponics/aquaponics setup; the garden planner skips chemistry rules in soil-bed mode.
Suitable systems: soil-bed, wicking.
Avoid in: nft, dwc, media-bed, drip, dutch-bucket.
Vermiculite
Also known as: Expanded mica
- Holds 3-4 times its weight in water: excellent for seed germination and seedling propagation, dangerous for mature plant roots which can drown
- Almost always mixed with perlite for active growing (perlite provides air, vermiculite provides water reserve)
- Compresses heavily over time; one or two crop cycles before replacement
- Has cation-exchange capacity; can mask early Mg/Ca deficiency similar to coco coir
Primarily used for seed-starting in plug trays, not for the active growing medium of a hydroponics system. Modern vermiculite is asbestos-free; older bulk products (pre-1990s, Libby MT mine) may not be. Buy horticultural-grade from a reputable supplier.
Suitable systems: wicking, soil-bed.
Avoid in: nft, dwc, media-bed, drip.