What the substrate needs to do
Use a clean soil-style substrate for Psalmopoeus cambridgei that can hold its shape without becoming hard, dusty or permanently waterlogged.
For Psalmopoeus cambridgei, the substrate in a Trinidad Chevron enclosure should support normal movement and retreat building. Heavy decor must not be able to collapse if the spider digs underneath it.
Depth
Trinidad Chevrons are arboreal, so substrate is mainly there to manage moisture, catch waste and support the lower part of the enclosure. Psalmopoeus cambridgei still needs enough depth for stable planting or cork placement, but the main retreat belongs above ground.
Match substrate depth to the current size of Psalmopoeus cambridgei. Small slings and fossorial individuals often use proportionally more depth than a large settled terrestrial adult.
Moisture
For Trinidad Chevrons, maintain moderate moisture with strong ventilation and constant water. 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 Psalmopoeus cambridgei 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 Psalmopoeus cambridgei does not collapse immediately. The upper surface can remain looser where appropriate.
For Psalmopoeus cambridgei, keep rocks, heavy cork and ornaments in a Trinidad Chevron enclosure low and secure so excavation cannot undermine them.
When substrate needs replacing
Spot-clean waste and prey remains from the Psalmopoeus cambridgei enclosure. Normal digging, webbing or rearrangement by the spider is not a reason to replace clean substrate.
For Psalmopoeus cambridgei, replace all substrate for a Trinidad Chevron only when it is fouled, contaminated, persistently mouldy or no longer structurally usable.