diff --git a/backend/src/acidwatch_api/models/arcs.py b/backend/src/acidwatch_api/models/arcs.py
index bbfa68d..dc4c7b7 100644
--- a/backend/src/acidwatch_api/models/arcs.py
+++ b/backend/src/acidwatch_api/models/arcs.py
@@ -33,7 +33,7 @@ def convert_to_arcs_simulation_request(
 async def post_arcs_run(
     simulation_request: SimulationRequest,
     jwt_token: Annotated[str, oauth2_scheme],
-) -> dict:
+) -> SimulationResults:
     arcs_simulation_request = convert_to_arcs_simulation_request(simulation_request)
     async with httpx.AsyncClient() as client:
         res = await client.post(
diff --git a/backend/src/acidwatch_api/models/co2spec.py b/backend/src/acidwatch_api/models/co2spec.py
index 4f80818..163bb78 100644
--- a/backend/src/acidwatch_api/models/co2spec.py
+++ b/backend/src/acidwatch_api/models/co2spec.py
@@ -60,14 +60,14 @@ class RunReactionResult(BaseModel):
 
 def convert_to_concentrations(simulation_request: SimulationRequest) -> Concentrations:
     return Concentrations(
-        h2o=simulation_request.concs.get("H2O", 0.0),
-        o2=simulation_request.concs.get("O2", 0.0),
-        so2=simulation_request.concs.get("SO2", 0.0),
-        no2=simulation_request.concs.get("NO2", 0.0),
-        h2s=simulation_request.concs.get("H2S", 0.0),
-        no=simulation_request.concs.get("NO", 0.0),
-        h2so4=simulation_request.concs.get("H2SO4", 0.0),
-        hno3=simulation_request.concs.get("HNO3", 0.0),
+        h2o=simulation_request.concs.get("H2O", 0.0) * 1e6,
+        o2=simulation_request.concs.get("O2", 0.0) * 1e6,
+        so2=simulation_request.concs.get("SO2", 0.0) * 1e6,
+        no2=simulation_request.concs.get("NO2", 0.0) * 1e6,
+        h2s=simulation_request.concs.get("H2S", 0.0) * 1e6,
+        no=simulation_request.concs.get("NO", 0.0) * 1e6,
+        h2so4=simulation_request.concs.get("H2SO4", 0.0) * 1e6,
+        hno3=simulation_request.concs.get("HNO3", 0.0) * 1e6,
     )
 
 
diff --git a/backend/tests/test_models_endpoints.py b/backend/tests/test_models_endpoints.py
index 1beb9f4..99b2cee 100644
--- a/backend/tests/test_models_endpoints.py
+++ b/backend/tests/test_models_endpoints.py
@@ -19,5 +19,4 @@ def test_get_models():
     client = TestClient(app)
     response = client.get("/models")
     assert response.status_code == 200
-    assert len(response.json()) == 3
-    assert all("name" in m for m in response.json())
+    assert len(response.json()) == 2