Water dish
Clean and refill the water dish for Cyriocosmus aueri whenever it becomes dirty or filled with substrate. A dish being repeatedly buried is not a reason to remove it.
Place the dish in the Peruvian Dwarf Tarantula enclosure where it can be reached without pulling apart the main retreat every time it needs cleaning.
Food remains and waste
Remove accessible prey remains and obvious waste from the Cyriocosmus aueri enclosure before they sit in damp substrate and begin to mould.
Spot-cleaning is normally enough for a Peruvian Dwarf Tarantula. There is no need to replace clean substrate simply because the spider has moved it around.
Leave useful webbing and burrows alone
For Cyriocosmus aueri, a stable burrow, webbed retreat or rearranged entrance is part of normal enclosure use. Cleaning should not mean rebuilding the spider's home after every feeding.
Only disturb the main retreat of a Peruvian Dwarf Tarantula when there is a real problem such as contamination, unsafe decor or a rehouse that genuinely needs to happen.
Mould and persistent dampness
For Cyriocosmus aueri, use lightly to moderately moist lower substrate with ventilation; never waterlogged. If mould keeps returning across the surface, look at watering and ventilation instead of repeatedly replacing otherwise clean substrate.
A small isolated patch can often be removed during normal cleaning, but a stale or persistently wet Peruvian Dwarf Tarantula enclosure needs the cause corrected.
When a full clean is justified
A full substrate change for Cyriocosmus aueri is reasonable when the enclosure is badly fouled, chemically contaminated, structurally unsafe or affected by a problem that spot-cleaning cannot solve.
Prepare replacement substrate and decor before moving a Peruvian Dwarf Tarantula. A planned clean is safer than improvising while the spider is exposed.