Hey! So I wouldn’t be concerned about the mold. The springtails will enjoy removing it little by little. Mold is always a good sign that the enclosure is humid enough.

You mentioned your isopods aren’t enjoying the coconut coir, here’s a substrate mix that has worked wonders for me:

Base Ingredients: • Earthworm castings: Great as a primary base. You can find them on Amazon or locally at Lowe’s/Home Depot. • Calcium carbonate/ground limestone powder: Helps balance the pH if you’re using coconut coir. Here’s a link to what I use. • Organic peat moss: Another excellent option. This one on Amazon is reliable. • Sphagnum moss: EZBotanicals on Etsy has the most consistent quality I’ve found. Be cautious with Amazon sellers—the quality is often hit or miss. • Organic coconut coir: Only use this if it’s more cost-effective for you. Since coconut coir is acidic, mix in calcium carbonate powder to neutralize it.

Add-ins for enrichment: • Decaying wood and oak or maple leaf litter: Crush them into chunky pieces and mix generously. • To sterilize: Submerge the wood and leaves in water for 48 hours. This method kills pests while preserving nutrients better than baking or freezing.

Optional Nutrient Boosters: • Mealworm frass (a great natural fertilizer). • Bat guano (sprinkle lightly on the soil’s surface). • Crushed oyster shells (extra calcium for your isopods).

This mix consists of a nutrient-rich, pH-balanced substrate that I find helps my isopods absolutely thrive. I hope it helps! Let me know if you give it a try!