What the substrate needs to do
Use a clean soil-style substrate for Nhandu tripepii that can hold its shape without becoming hard, dusty or permanently waterlogged.
For Nhandu tripepii, the substrate in a Brazilian Giant Blonde enclosure should support normal movement and retreat building. Heavy decor must not be able to collapse if the spider digs underneath it.
Depth
Brazilian Giant Blondes are terrestrial, so give Nhandu tripepii 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 Nhandu tripepii. Small slings and fossorial individuals often use proportionally more depth than a large settled terrestrial adult.
Moisture
For Brazilian Giant Blondes, keep a water dish available and maintain a moderate moisture gradient; keep good airflow. 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 Nhandu tripepii 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 Nhandu tripepii does not collapse immediately. The upper surface can remain looser where appropriate.
For Nhandu tripepii, keep rocks, heavy cork and ornaments in a Brazilian Giant Blonde enclosure low and secure so excavation cannot undermine them.
When substrate needs replacing
Spot-clean waste and prey remains from the Nhandu tripepii enclosure. Normal digging, webbing or rearrangement by the spider is not a reason to replace clean substrate.
For Nhandu tripepii, replace all substrate for a Brazilian Giant Blonde only when it is fouled, contaminated, persistently mouldy or no longer structurally usable.