The pack works alongside most standard data packs. It only clashes with other packs or mods that directly alter swamp biome files. If the pack is enabled but your swamps stay dark, a conflict is the most likely cause.
Spot the likely culprit
Check your other packs and mods for anything that changes swamps. Common examples:
- Terrain or biome overhauls that rework Swamp or Mangrove Swamp
- Packs that change swamp vegetation, water color or features
- World-generation mods that replace vanilla biomes
General packs that don't touch swamp biome files, such as recipe tweaks or loot changes, shouldn't interfere.
Isolate it step by step
1. Back up your world first.
2. Run /datapack list to see every enabled pack.
3. Disable a suspect pack with /datapack disable followed by its name. Tab-completion fills in the name.
4. Go to a Swamp or Mangrove Swamp at night and check for fireflies.
5. If they appear, you've found the conflict. If not, re-enable that pack and test the next one.
6. For mods, you'll need to remove them from your mods folder and restart the game to test.
Choosing what to keep
Once you know which pack conflicts, keep whichever you value more. You can also change the load order on the Data Packs screen to see whether one order gives the result you want. Because both packs edit the same swamp files, expect that only one of them can fully take effect.