SUBSTRATE & HARDSCAPE

Sand Substrate

Inert, rounded-grain sand — chemically neutral, but it compacts and needs root feeding.

Setup stage Substrate

Unplug before servicingHands out of the water firstDrip loop on every cableTest before you dose30 ppm CO₂ ceilingCycle before stocking

Substrate

Specification
Material	Quartz or river sand
Grain size	1–2 mm
Chemistry	Inert
Shape	Rounded or angular
Bed depth	3–4 cm max without disturbance
Colour	Natural, black, white

Technical parameters
pH effect	None
KH effect	None
Root feeding	Required for heavy feeders
Anaerobic risk	Rises above 4 cm depth
Vacuum method	Hover above surface
Corydoras suitability	Excellent — rounded grains

Sand is inert. It releases nothing and buffers nothing, so the water chemistry is whatever your tap water and your fertiliser dosing make it. For a fish that needs hard, alkaline water — or for a keeper who wants predictable parameters — that neutrality is the point.

Grain shape matters more than grain size. Rounded, river-worn sand settles into a dense bed that anaerobic pockets can form in, and those pockets produce hydrogen sulphide. Angular or coarser sand stays more open. The practical rule is 1–2 mm grain, no finer, and a bed no deeper than 4 cm unless you actively disturb it.

The other consequence of inertness is that rooted plants get nothing from it. A sand substrate needs root tabs pushed in beside heavy feeders, and carpeting plants spread more slowly across sand than across aqua soil. Sand is also unforgiving of vacuuming — a strong siphon lifts it out of the tank.

Safety and welfare

Never use builder's sand or play sand from a hardware store. It is not graded, may contain sharp fragments and can carry contaminants. Use aquarium-grade sand only.
Stir the top centimetre weekly with a skewer to stop anaerobic pockets forming. If you ever smell rotten eggs, you have a pocket — disturb it gently and do a large water change.
Wash sand in a bucket until the runoff runs clear before it goes anywhere near the tank.

Using it well

A black sand foreground makes the colours of plants and fish read much stronger than white sand, which blows out highlights.

If you want both soil and sand, put the sand in a shallow tray or behind a stone wall rather than mixing them at the boundary.

Root tabs every 8–12 weeks under heavy feeders. Sand holds nothing, so what you put in is what they get.

Best for

CorydorasGeophagusCherry shrimpNerite snailLake-style biotopes

Note. Parameters are conventional ranges across the category, not the claim of any one manufacturer. Nothing on this page is for sale and no outcome for any plant or animal is guaranteed. Simulator output elsewhere on this site is a simplified model, not a measurement — confirm everything with a test kit and the equipment's own instructions.

Sand Substrate

Using it well

Best for

Works alongside