diff --git a/Cargo.lock b/Cargo.lock
index fd33369..ad823d8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -168,7 +168,7 @@ checksum = "7a81dae078cea95a014a339291cec439d2f232ebe854a9d672b796c6afafa9b7"
 
 [[package]]
 name = "dive-deco"
-version = "2.1.0"
+version = "2.1.1"
 dependencies = [
  "criterion",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 2a67a17..85c1ce4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "dive-deco"
-version = "2.1.0"
+version = "2.1.1"
 edition = "2021"
 license = "MIT"
 description = "A dive decompression models library (Buehlmann ZH-L 16C)"
diff --git a/src/buehlmann/buehlmann_model.rs b/src/buehlmann/buehlmann_model.rs
index 3aebebd..7f5b70a 100644
--- a/src/buehlmann/buehlmann_model.rs
+++ b/src/buehlmann/buehlmann_model.rs
@@ -348,4 +348,23 @@ mod tests {
         let slope_point = model.gf_slope_point(gf, 33.528, 30.48);
         assert_eq!(slope_point, 35);
     }
+
+    #[test]
+    fn test_initial_supersaturation() {
+        fn extract_supersaturations(model: BuehlmannModel) -> Vec<Supersaturation> {
+            model.compartments.clone().into_iter().map(|comp| {
+            comp.supersaturation(model.config().surface_pressure, 0.)
+            }).collect::<Vec<Supersaturation>>()
+        }
+
+        let model_initial = BuehlmannModel::default();
+
+        let mut model_with_surface_interval = BuehlmannModel::default();
+        model_with_surface_interval.step(0., 999999, &Gas::air());
+
+        let initial_gfs = extract_supersaturations(model_initial);
+        let surface_interval_gfs = extract_supersaturations(model_with_surface_interval);
+
+        assert_eq!(initial_gfs, surface_interval_gfs);
+    }
 }
diff --git a/src/buehlmann/compartment.rs b/src/buehlmann/compartment.rs
index a061c51..b2ed8d3 100644
--- a/src/buehlmann/compartment.rs
+++ b/src/buehlmann/compartment.rs
@@ -32,7 +32,10 @@ impl Compartment {
         model_config: BuehlmannConfig,
     ) -> Self {
         let init_gas = Gas::air();
-        let init_gas_compound_pressures = init_gas.gas_pressures_compound(1.);
+        let init_gas_compound_pressures = init_gas.inspired_partial_pressures(
+            0.,
+            model_config.surface_pressure
+        );
         let n2_ip = init_gas_compound_pressures.n2;
         let he_ip = init_gas_compound_pressures.he;
 
@@ -179,11 +182,11 @@ mod tests {
             comp,
             Compartment {
                 no: 1,
-                params: (4., 1.2599, 0.5050, 1.51, 01.7424, 0.4245),
-                he_ip: 0.,
-                n2_ip: 0.79,
-                total_ip: 0.79,
-                min_tolerable_amb_pressure: -0.2372995,
+                min_tolerable_amb_pressure: -0.257127315,
+                he_ip: 0.0,
+                n2_ip: 0.750737,
+                total_ip: 0.750737,
+                params: (4.0, 1.2599, 0.505, 1.51, 1.7424, 0.4245),
                 // mocked config and state
                 model_config: BuehlmannConfig::default(),
             }
@@ -196,7 +199,7 @@ mod tests {
         let air = Gas::new(0.21, 0.);
         let step = StepData { depth: 30., time: (10 * 60), gas: &air };
         comp.recalculate(&step, 100, 1000);
-        assert_eq!(comp.total_ip, 1.315391144211091);
+        assert_eq!(comp.total_ip, 1.2850179204911072);
     }
 
     #[test]
@@ -213,7 +216,7 @@ mod tests {
         let step = StepData { depth: 30., time: (10 * 60), gas: &air };
         comp.recalculate(&step, 100, 100);
         let min_tolerable_pressure = comp.min_tolerable_amb_pressure;
-        assert_eq!(min_tolerable_pressure, 0.4342609809161748);
+        assert_eq!(min_tolerable_pressure, 0.40957969932131577);
     }
 
 }
diff --git a/tests/buehlmann_tests.rs b/tests/buehlmann_tests.rs
index 87a37c3..89ce044 100644
--- a/tests/buehlmann_tests.rs
+++ b/tests/buehlmann_tests.rs
@@ -19,10 +19,10 @@ fn test_gfs() {
     let air = Gas::new(0.21, 0.);
 
     model.step(50., 20 * 60, &air);
-    assert_eq!(model.supersaturation(), Supersaturation { gf_99: 0., gf_surf: 194.3055827400852 });
+    assert_eq!(model.supersaturation(), Supersaturation { gf_99: 0., gf_surf: 193.8554997961134 });
 
     model.step(40., 10 * 60, &air);
-    assert_eq!(model.supersaturation(), Supersaturation { gf_99: 0., gf_surf: 209.1025059770294 });
+    assert_eq!(model.supersaturation(), Supersaturation { gf_99: 0., gf_surf: 208.00431699178796 });
 }
 
 #[test]
@@ -117,7 +117,7 @@ fn test_altitude() {
     let air = Gas::new(0.21, 0.);
     model.step(40., 60 * 60, &air);
     let Supersaturation { gf_surf, ..} = model.supersaturation();
-    assert_eq!(gf_surf, 314.27462637570085);
+    assert_eq!(gf_surf, 299.023204474694);
 }
 
 #[test]
@@ -133,7 +133,7 @@ fn test_example_deco_start() {
 
     // instant drop to 40m on air for 10min
     model.step(40., 10 * 60, &air);
-    assert_eq!(model.ceiling(), 12.906758687930836);
+    assert_eq!(model.ceiling(), 12.85312294790554);
 }
 
 #[test]
@@ -151,7 +151,7 @@ fn test_example_deco() {
     model.step(30., 3 * 60, &air);
     model.step(21., 10 * 60, &ean_50);
 
-    assert_eq!(model.ceiling(), 11.744868181179458);
+    assert_eq!(model.ceiling(), 12.455491216740299);
 }
 
 #[test]
diff --git a/tests/deco_tests.rs b/tests/deco_tests.rs
index cf7f044..9149dcf 100644
--- a/tests/deco_tests.rs
+++ b/tests/deco_tests.rs
@@ -24,7 +24,7 @@ fn test_deco_single_gas() {
         tts
     } = model.deco(vec![air]);
 
-    assert_close_to_percent!(tts as f64, 800., 1.); // 13.(3) min todo round to 14
+    assert_close_to_percent!(tts as f64, 754., 1.); // 13.(3) min todo round to 14
     assert_eq!(deco_stages.len(), 5);
 
     let expected_deco_stages =  vec![
@@ -39,7 +39,7 @@ fn test_deco_single_gas() {
             stage_type: DecoStageType::DecoStop,
             start_depth: 6.0,
             end_depth: 6.0,
-            duration: 95,
+            duration: 88,
             gas: air
         },
         DecoStage {
@@ -53,7 +53,7 @@ fn test_deco_single_gas() {
             stage_type: DecoStageType::DecoStop,
             start_depth: 3.0,
             end_depth: 3.0,
-            duration: 436,
+            duration: 400,
             gas: air
         },
         DecoStage {
@@ -108,7 +108,7 @@ fn test_deco_multi_gas() {
             stage_type: DecoStageType::DecoStop,
             start_depth: 6.0,
             end_depth: 6.0,
-            duration: 39,
+            duration: 34,
             gas: ean_50
         },
         DecoStage {
@@ -122,7 +122,7 @@ fn test_deco_multi_gas() {
             stage_type: DecoStageType::DecoStop,
             start_depth: 3.0,
             end_depth: 3.0,
-            duration: 301,
+            duration: 291,
             gas: ean_50
         },
         DecoStage {
@@ -168,7 +168,7 @@ fn test_deco_with_deco_mod_at_bottom() {
             stage_type: DecoStageType::DecoStop,
             start_depth: 3.0,
             end_depth: 3.0,
-            duration: 300,
+            duration: 268,
             gas: ean_36,
         },
         DecoStage {
@@ -181,7 +181,7 @@ fn test_deco_with_deco_mod_at_bottom() {
     ];
 
     assert_deco_stages_eq(deco_stages, expected_deco_stages);
-    assert_eq!(tts, 500);
+    assert_eq!(tts, 468);
 }
 
 fn assert_deco_stages_eq(deco_stages: Vec<DecoStage>, expected_deco_stages: Vec<DecoStage>) {
diff --git a/tests/gradient_factors_tests.rs b/tests/gradient_factors_tests.rs
index c3de73b..09898df 100644
--- a/tests/gradient_factors_tests.rs
+++ b/tests/gradient_factors_tests.rs
@@ -7,10 +7,10 @@ fn test_ndl() {
     let test_cases: Vec<(GradientFactors, Depth, Minutes)> = vec![
         // 100/100
         ((100, 100), 21., 40),
-        ((100, 100), 15., 88),
+        ((100, 100), 15., 90),
 
         // 70/70
-        ((70, 70), 21., 18),
+        ((70, 70), 21., 19),
         ((70, 70), 15., 47),
     ];
 
diff --git a/tests/helium_tests.rs b/tests/helium_tests.rs
index 79a7a00..598cd51 100644
--- a/tests/helium_tests.rs
+++ b/tests/helium_tests.rs
@@ -12,7 +12,7 @@ fn test_tmx_gf_surf() {
 
     let Supersaturation { gf_surf, .. } = model.supersaturation();
 
-    assert_close_to_percent!(gf_surf, 335.77, 0.5);
+    assert_close_to_percent!(gf_surf, 335.77, 1.);
 }
 
 #[test]
@@ -24,7 +24,7 @@ fn test_tmx_ndl() {
     let step = StepData { depth: 20., time: 0, gas: &tmx };
     model.step(step.depth, step.time, step.gas);
 
-    assert_eq!(model.ndl(), 16);
+    assert_eq!(model.ndl(), 17);
 }
 
 
@@ -40,5 +40,5 @@ fn test_heliox_gf_surf() {
 
     let Supersaturation { gf_surf, .. } = model.supersaturation();
 
-    assert_close_to_percent!(gf_surf, 201.16, 0.5);
+    assert_close_to_percent!(gf_surf, 197.93, 1.);
 }