diff --git a/exercises/exercise-biomineralization/fluidsystems/biomin.hh b/exercises/exercise-biomineralization/fluidsystems/biomin.hh
index ae2632fcdeea6997cdab89eed0968449a4ce8996..7091e5dbe2eaf1595cd18be6218347dfebd057f0 100644
--- a/exercises/exercise-biomineralization/fluidsystems/biomin.hh
+++ b/exercises/exercise-biomineralization/fluidsystems/biomin.hh
@@ -265,11 +265,7 @@ public:
         switch (phaseIdx) {
             // assume pure brine for the liquid phase.
             case liquidPhaseIdx:
-                return liquidDensity_(temperature,
-                                      pressure,
-                                      fluidState.moleFraction(liquidPhaseIdx, CO2Idx),
-                                      fluidState.moleFraction(liquidPhaseIdx, H2OIdx),
-                                      fluidState.massFraction(liquidPhaseIdx, CaIdx)); //consider density effect of dissolved calcium
+                return Brine::liquidDensity(temperature, pressure); //TODO major assumption in favor of runtime! Not considering density effect of dissolved calcium
 
             // assume pure CO2 for the gas phase.
             case gasPhaseIdx:
@@ -299,7 +295,7 @@ public:
         if (phaseIdx == liquidPhaseIdx)
         {
             return density(fluidState, paramCache, phaseIdx)
-                   / fluidState.averageMolarMass(phaseIdx);
+                   / Brine::molarMass();
         }
         else if (phaseIdx == gasPhaseIdx)
         {
@@ -502,56 +498,6 @@ public:
         }
     };
 
-private:
-    //! calculate liquid density with respect to Water, CO2 and salt
-    static Scalar liquidDensity_(Scalar T,
-                                 Scalar pl,
-                                 Scalar xwCO2,
-                                 Scalar xwH2O,
-                                 Scalar XlSal)
-    {
-        if(T < 273.15)
-        {
-            DUNE_THROW(NumericalProblem,
-                       "Liquid density for Brine and CO2 is only "
-                       "defined above 273.15K (is" << T << ")");
-        }
-        if(pl >= 2.5e8)
-        {
-            DUNE_THROW(NumericalProblem,
-                       "Liquid density for Brine and CO2 is only "
-                       "defined below 250MPa (is" << pl << ")");
-        }
-
-        const Scalar rho_brine = Brine::liquidDensity(T, pl);
-        const Scalar rho_pure = H2O::liquidDensity(T, pl);
-        const Scalar rho_lCO2 = liquidDensityWaterCO2_(T, pl, xwH2O, xwCO2);
-        const Scalar contribCO2 = rho_lCO2 - rho_pure;
-        return rho_brine + contribCO2;
-    }
-
-    //! calculate liquid Density of water and CO2
-    static Scalar liquidDensityWaterCO2_(Scalar temperature,
-                                         Scalar pl,
-                                         Scalar xwH2O,
-                                         Scalar xwCO2)
-    {
-        const Scalar M_CO2 = CO2::molarMass();
-        const Scalar M_H2O = H2O::molarMass();
-
-        const Scalar tempC = temperature - 273.15;        /* tempC : temperature in °C */
-        const Scalar rho_pure = H2O::liquidDensity(temperature, pl);
-        xwH2O = 1.0 - xwCO2; // xwH2O is available, but in case of a pure gas phase
-                             // the value of M_T for the virtual liquid phase can become very large
-        const Scalar M_T = M_H2O * xwH2O + M_CO2 * xwCO2;
-        const Scalar V_phi =
-            (37.51 +
-             tempC*(-9.585e-2 +
-                    tempC*(8.74e-4 -
-                           tempC*5.044e-7))) / 1.0e6;
-        return 1 / (xwCO2 * V_phi/M_T + M_H2O * xwH2O / (rho_pure * M_T));
-    }
-
 };
 
 } // end namespace FluidSystems
diff --git a/exercises/solution/exercise-biomineralization/fluidsystems/biomin.hh b/exercises/solution/exercise-biomineralization/fluidsystems/biomin.hh
index ae2632fcdeea6997cdab89eed0968449a4ce8996..0ef40f34993ca5b146da7666e473c9036d839414 100644
--- a/exercises/solution/exercise-biomineralization/fluidsystems/biomin.hh
+++ b/exercises/solution/exercise-biomineralization/fluidsystems/biomin.hh
@@ -232,7 +232,7 @@ public:
     static void init()
     {
         init(/*startTemp=*/295.15, /*endTemp=*/305.15, /*tempSteps=*/10,
-             /*startPressure=*/1e4, /*endPressure=*/1e6, /*pressureSteps=*/200);
+             /*startPressure=*/1e4, /*endPressure=*/1e6, /*pressureSteps=*/2000);
 
     }
 
@@ -265,11 +265,7 @@ public:
         switch (phaseIdx) {
             // assume pure brine for the liquid phase.
             case liquidPhaseIdx:
-                return liquidDensity_(temperature,
-                                      pressure,
-                                      fluidState.moleFraction(liquidPhaseIdx, CO2Idx),
-                                      fluidState.moleFraction(liquidPhaseIdx, H2OIdx),
-                                      fluidState.massFraction(liquidPhaseIdx, CaIdx)); //consider density effect of dissolved calcium
+                return Brine::liquidDensity(temperature, pressure); //TODO major assumption in favor of runtime! Not considering density effect of dissolved calcium
 
             // assume pure CO2 for the gas phase.
             case gasPhaseIdx:
@@ -299,7 +295,7 @@ public:
         if (phaseIdx == liquidPhaseIdx)
         {
             return density(fluidState, paramCache, phaseIdx)
-                   / fluidState.averageMolarMass(phaseIdx);
+                   / Brine::molarMass();
         }
         else if (phaseIdx == gasPhaseIdx)
         {
@@ -502,56 +498,6 @@ public:
         }
     };
 
-private:
-    //! calculate liquid density with respect to Water, CO2 and salt
-    static Scalar liquidDensity_(Scalar T,
-                                 Scalar pl,
-                                 Scalar xwCO2,
-                                 Scalar xwH2O,
-                                 Scalar XlSal)
-    {
-        if(T < 273.15)
-        {
-            DUNE_THROW(NumericalProblem,
-                       "Liquid density for Brine and CO2 is only "
-                       "defined above 273.15K (is" << T << ")");
-        }
-        if(pl >= 2.5e8)
-        {
-            DUNE_THROW(NumericalProblem,
-                       "Liquid density for Brine and CO2 is only "
-                       "defined below 250MPa (is" << pl << ")");
-        }
-
-        const Scalar rho_brine = Brine::liquidDensity(T, pl);
-        const Scalar rho_pure = H2O::liquidDensity(T, pl);
-        const Scalar rho_lCO2 = liquidDensityWaterCO2_(T, pl, xwH2O, xwCO2);
-        const Scalar contribCO2 = rho_lCO2 - rho_pure;
-        return rho_brine + contribCO2;
-    }
-
-    //! calculate liquid Density of water and CO2
-    static Scalar liquidDensityWaterCO2_(Scalar temperature,
-                                         Scalar pl,
-                                         Scalar xwH2O,
-                                         Scalar xwCO2)
-    {
-        const Scalar M_CO2 = CO2::molarMass();
-        const Scalar M_H2O = H2O::molarMass();
-
-        const Scalar tempC = temperature - 273.15;        /* tempC : temperature in °C */
-        const Scalar rho_pure = H2O::liquidDensity(temperature, pl);
-        xwH2O = 1.0 - xwCO2; // xwH2O is available, but in case of a pure gas phase
-                             // the value of M_T for the virtual liquid phase can become very large
-        const Scalar M_T = M_H2O * xwH2O + M_CO2 * xwCO2;
-        const Scalar V_phi =
-            (37.51 +
-             tempC*(-9.585e-2 +
-                    tempC*(8.74e-4 -
-                           tempC*5.044e-7))) / 1.0e6;
-        return 1 / (xwCO2 * V_phi/M_T + M_H2O * xwH2O / (rho_pure * M_T));
-    }
-
 };
 
 } // end namespace FluidSystems