What the substrate needs to do
Use a clean soil-style substrate for Aphonopelma chalcodes that can hold its shape without becoming hard, dusty or permanently waterlogged.
For Aphonopelma chalcodes, the substrate in an Arizona Blonde Tarantula enclosure should support normal movement and retreat building. Heavy decor must not be able to collapse if the spider digs underneath it.
Depth
Arizona Blonde Tarantulas are terrestrial, so give Aphonopelma chalcodes enough substrate for normal digging while also keeping the fall distance from the lid low. A stable ground-level hide should sit securely on or in the substrate.
Match substrate depth to the current size of Aphonopelma chalcodes. Small slings and fossorial individuals often use proportionally more depth than a large settled terrestrial adult.
Moisture
For Arizona Blonde Tarantulas, keep the surface mostly dry with clean water available; modest moisture for smaller slings. Add water in a controlled area and judge how the enclosure changes over several days instead of trying to keep every centimetre equally wet.
Substrate moisture for Aphonopelma chalcodes should work together with ventilation. Persistent condensation, a stale smell or widespread mould usually means the setup is staying too wet.
Compaction and stability
Press the lower substrate layers firmly enough that a retreat or burrow for Aphonopelma chalcodes does not collapse immediately. The upper surface can remain looser where appropriate.
For Aphonopelma chalcodes, keep rocks, heavy cork and ornaments in an Arizona Blonde Tarantula enclosure low and secure so excavation cannot undermine them.
When substrate needs replacing
Spot-clean waste and prey remains from the Aphonopelma chalcodes enclosure. Normal digging, webbing or rearrangement by the spider is not a reason to replace clean substrate.
For Aphonopelma chalcodes, replace all substrate for an Arizona Blonde Tarantula only when it is fouled, contaminated, persistently mouldy or no longer structurally usable.