diff --git a/src/specmicp/adimensional/adimensional_system.cpp b/src/specmicp/adimensional/adimensional_system.cpp
index 42fa252..3cd2da3 100644
--- a/src/specmicp/adimensional/adimensional_system.cpp
+++ b/src/specmicp/adimensional/adimensional_system.cpp
@@ -1,668 +1,687 @@
 /*-------------------------------------------------------
 
  - Module : specmicp
  - File : adim_system.cpp
  - Author : Fabien Georget
 
 Copyright (c) 2014, Fabien Georget <fabieng@princeton.edu>, Princeton University
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:
     * Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
     * Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.
     * Neither the name of the Princeton University nor the
       names of its contributors may be used to endorse or promote products
       derived from this software without specific prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 ---------------------------------------------------------*/
 //#include <iostream>
 
 #include <cmath>
 #include "adimensional_system.hpp"
 #include "utils/log.hpp"
 #include "../equilibrium_data.hpp"
 
 #include "physics/constants.hpp"
 #include "physics/laws.hpp"
 
 #include "adimensional_system_solution.hpp"
 
 //#define SPECMICP_DEBUG_EQUATION_FD_JACOBIAN
 
 namespace specmicp {
 
 constexpr scalar_t log10 = std::log(10.0);
 
 AdimensionalSystem::AdimensionalSystem(
         RawDatabasePtr ptrdata,
         const Vector &totconc,
         const AdimensionalSystemOptions& options)
     :
       OptionsHandler<AdimensionalSystemOptions>(options),
       m_data(ptrdata),
       m_tot_conc(totconc),
       m_secondary_conc(ptrdata->nb_aqueous),
       m_loggamma(ptrdata->nb_component+ptrdata->nb_aqueous),
       m_saturation_gas(0),
       m_gas_fugacity(ptrdata->nb_gas)
 {
     number_eq();
     m_secondary_conc.setZero();
     m_gas_fugacity.setZero();
     m_loggamma.setZero();
 }
 
 
 AdimensionalSystem::AdimensionalSystem(
         RawDatabasePtr ptrdata,
         const Vector& totconc,
         const AdimensionalSystemSolution& previous_solution,
         const AdimensionalSystemOptions& options
         ):
     OptionsHandler<AdimensionalSystemOptions>(options),
     m_data(ptrdata),
     m_tot_conc(totconc),
     m_secondary_conc(previous_solution.secondary_molalities),
     m_loggamma(previous_solution.log_gamma),
     m_ionic_strength(previous_solution.ionic_strength),
     m_saturation_gas(0),
     m_gas_fugacity(ptrdata->nb_gas)
 {
     number_eq();
     m_gas_fugacity.setZero();
 
 }
 
 
 void AdimensionalSystem::number_eq()
 {
     index_t neq = 0;
     m_ideq.reserve(m_data->nb_component+m_data->nb_mineral);
+    m_aqueous_component_equation_type.reserve(m_data->nb_component);
     if (get_options().conservation_water)
     {
         m_ideq.push_back(neq);
+        m_aqueous_component_equation_type.push_back(AqueousComponentEquationType::MassConservation);
         ++neq;
     } else {
         m_ideq.push_back(no_equation);
+        m_aqueous_component_equation_type.push_back(AqueousComponentEquationType::NoEquation);
     }
     for (index_t i: m_data->range_aqueous_component())
     {
         // Remove components that does not exist
         if (m_tot_conc(i) == 0 and i!= 1)
         {
             INFO << "Component " << m_data->labels_basis[i]
                  << "has total concentration equal to zero, we desactivate it" << std::endl;
             m_nonactive_component.push_back(i);
             m_ideq.push_back(no_equation);
+            m_aqueous_component_equation_type.push_back(AqueousComponentEquationType::NoEquation);
             continue;
         }
         else
         {
             m_ideq.push_back(neq);
+            if (get_options().charge_keeper == i) {
+                m_aqueous_component_equation_type.push_back(AqueousComponentEquationType::ChargeBalance);
+            }
+            else {
+                m_aqueous_component_equation_type.push_back(AqueousComponentEquationType::MassConservation);
+            }
             ++neq;
         }
     }
     m_nb_free_vars = neq;
     for (index_t m: m_data->range_mineral())
     {
         bool can_precipitate = true;
         // Remove minerals that cannot precipitate
         for (auto it=m_nonactive_component.begin(); it!=m_nonactive_component.end(); ++it)
         {
             if (m_data->nu_mineral(m, *it) != 0)
             {
                 can_precipitate = false;
                 break; // this is not a mineral that can precipitate
             }
         }
         if (can_precipitate)
         {
             m_ideq.push_back(neq);
             ++neq;
         }
         else
         {
             m_ideq.push_back(no_equation);
         }
     }
     m_nb_tot_vars = neq;
     m_nb_compl_vars = m_nb_tot_vars - m_nb_free_vars;
     // aqueous species
     m_active_aqueous.reserve(m_data->nb_aqueous);
     for (index_t j: m_data->range_aqueous())
     {
         bool can_exist = true;
         for (auto it=m_nonactive_component.begin(); it!=m_nonactive_component.end(); ++it)
         {
             if (m_data->nu_aqueous(j,*it) != 0)
             {
                 can_exist = false;
             }
         }
         m_active_aqueous.push_back(can_exist);
     }
     m_active_gas.reserve(m_data->nb_gas);
     for (index_t k: m_data->range_gas())
     {
         bool can_exist = true;
         for (auto it=m_nonactive_component.begin(); it!=m_nonactive_component.end(); ++it)
         {
             if (m_data->nu_gas(k,*it) != 0)
             {
                 can_exist = false;
             }
         }
         m_active_gas.push_back(can_exist);
     }
 }
 
 scalar_t AdimensionalSystem::saturation_water(const Vector& x) const
 {
     if (ideq_w() != no_equation)
         return x(ideq_w());
     else
         return 1.0 - sum_saturation_minerals(x);
 }
 
 scalar_t AdimensionalSystem::saturation_mineral(const Vector& x, index_t mineral) const
 {
     specmicp_assert(mineral >= 0 and mineral < m_data->nb_mineral);
     if (ideq_min(mineral) == no_equation) return 0.0;
     else return x(ideq_min(mineral));
 }
 
 scalar_t AdimensionalSystem::sum_saturation_minerals(const Vector& x) const
 {
     scalar_t sum_saturations = 0.0;
     for (index_t mineral: m_data->range_mineral())
     {
         sum_saturations += saturation_mineral(x, mineral);
     }
     return sum_saturations;
 }
 
 scalar_t AdimensionalSystem::density_water() const
 {
     return laws::density_water(units::celsius(25.0), length_unit(), mass_unit());
 }
 
 scalar_t AdimensionalSystem::molar_volume_mineral(index_t mineral) const
 {
     return m_data->molar_volume_mineral(mineral, length_unit());
 }
 
 scalar_t AdimensionalSystem::residual_water(const Vector& x) const
 {
     const scalar_t conc_w = density_water()*saturation_water(x);
     scalar_t res = m_tot_conc(0) - conc_w/m_data->molar_mass_basis_si(0);
     for (index_t j: m_data->range_aqueous())
     {
         if (not is_aqueous_active(j)) continue;
         res -= conc_w*m_data->nu_aqueous(j, 0)*m_secondary_conc(j);
     }
     for (index_t m: m_data->range_mineral())
     {
         if (ideq_min(m) == no_equation or m_data->nu_mineral(m, 0) == 0.0) continue;
         res -= m_data->nu_mineral(m, 0)*saturation_mineral(x, m)/molar_volume_mineral(m);
     }
     for (index_t k: m_data->range_gas())
     {
         if (m_data->nu_gas(k, 0) == 0.0) continue;
         res -= m_data->nu_gas(k, 0)*saturation_gas_phase()*gas_fugacity(k)/(
                     constants::gas_constant*gas_total_pressure()*temperature());
     }
     return res;
 }
 
 
 double AdimensionalSystem::residual_component(const Vector &x, index_t component) const
 {
     const scalar_t conc_w = density_water()*saturation_water(x);
     scalar_t res = m_tot_conc(component) - conc_w*component_molality(x, component);
     for (index_t j: m_data->range_aqueous())
     {
         if (not is_aqueous_active(j)) continue;
         res -= conc_w*m_data->nu_aqueous(j, component)*secondary_molality(j);
     }
     for (index_t m: m_data->range_mineral())
     {
         if (ideq_min(m) == no_equation) continue;
         res -= m_data->nu_mineral(m, component)*saturation_mineral(x, m)/molar_volume_mineral(m);
     }
     for (index_t k: m_data->range_gas())
     {
         if (m_data->nu_gas(k, component) == 0.0) continue;
         res -= m_data->nu_gas(k, component)*saturation_gas_phase()*gas_fugacity(k)/(
                     constants::gas_constant*gas_total_pressure()*temperature());
     }
     return res;
 }
 
 
 double AdimensionalSystem::residual_mineral(const Vector& x, index_t m) const
 {
     scalar_t res = m_data->logk_mineral(m);
     for (index_t i: m_data->range_aqueous_component())
     {
         if (m_data->nu_mineral(m, i) != 0)
             res -= m_data->nu_mineral(m, i)*(log_component_molality(x, i) + log_gamma_component(i));
     }
     return res;
 }
 
 double AdimensionalSystem::residual_charge_conservation(const Vector& x) const
 {
     scalar_t res = 0.0;
     for (index_t i: m_data->range_aqueous_component())
     {
         if (m_data->charge_component(i) != 0 and ideq_paq(i) != no_equation)
             res += m_data->charge_component(i)*component_molality(x, i);
     }
     for (index_t j: m_data->range_aqueous())
     {
         if (m_data->charge_aqueous(j) == 0 and  not is_aqueous_active(j)) continue;
         res += m_data->charge_aqueous(j)*secondary_molality(j);
     }
     return res;
 }
 
 void AdimensionalSystem::get_residuals(const Vector& x, Vector& residual)
 {
     set_secondary_concentration(x);
     if (ideq_w() != no_equation) residual(ideq_w()) = residual_water(x);
     for (index_t i: m_data->range_aqueous_component())
     {
-        if (ideq_paq(i) == no_equation)  continue;
-        if (is_charge_keeper(i)) residual(ideq_paq(i)) = residual_charge_conservation(x);
-        else residual(ideq_paq(i)) = residual_component(x, i);
+        switch (aqueous_component_equation_type(i))
+        {
+        case AqueousComponentEquationType::NoEquation:
+            continue;
+        case AqueousComponentEquationType::ChargeBalance:
+            residual(ideq_paq(i)) = residual_charge_conservation(x);
+            break;
+        default:
+            residual(ideq_paq(i)) = residual_component(x, i);
+        }
     }
     for (index_t m: m_data->range_mineral())
     {
         if (ideq_min(m) != no_equation) residual(ideq_min(m)) = residual_mineral(x, m);
     }
 }
 
 
 
 void AdimensionalSystem::get_jacobian(Vector& x, Matrix& jacobian)
 // //non-optimized Finite difference, for test only
 #ifdef SPECMICP_DEBUG_EQUATION_FD_JACOBIAN
 {
     const int neq = total_variables();
     Eigen::VectorXd res(total_variables());
     Eigen::VectorXd perturbed_res(total_variables());
 
     get_residuals(x, res);
     for (int j=0; j<neq; ++j)
     {
         double h = 1e-8*std::abs(x(j));
         //h = std::copysign(h, x(j));
         if (h==0) h = 1e-8;
         double tmp = x(j);
         x(j) += h;
         h = x(j) - tmp;
         get_residuals(x, perturbed_res);
         for (int i=0; i<neq; ++i)
         {
             jacobian(i, j) = (perturbed_res(i) - res(i))/h;
         }
         x(j) = tmp;
     }
  std::cout << jacobian << std::endl;
     return;
 }
 #else // analytical jacobian
 {
     jacobian.resize(total_variables(), total_variables());
     jacobian.setZero();
     // water
     jacobian_water(x, jacobian);
     // aqueous component
     jacobian_aqueous_components(x, jacobian);
     // mineral equilibrium
     jacobian_minerals(x, jacobian);
 }
 #endif
 
 void AdimensionalSystem::jacobian_water(Vector& x, Matrix& jacobian)
 {
     if (ideq_w() != no_equation)
     {
         scalar_t tmp = -density_water()/m_data->molar_mass_basis_si(0);
         for (index_t j: m_data->range_aqueous())
         {
             if ( m_data->nu_aqueous(j, 0) == 0 and not is_aqueous_active(j)) continue;
             tmp -= m_data->nu_aqueous(j, 0)*secondary_molality(j);
         }
         jacobian(0, 0) = tmp;
         const scalar_t conc_w = density_water()*saturation_water(x);
         for (index_t k: m_data->range_aqueous_component())
         {
             if (ideq_paq(k) == no_equation) continue;
             scalar_t tmp = 0;
             for (index_t j: m_data->range_aqueous())
             {
                 tmp -= m_data->nu_aqueous(j,0)*m_data->nu_aqueous(j,k)*secondary_molality(j);
             }
             jacobian(0, ideq_paq(k)) = conc_w*log10 * tmp;
         }
         for (index_t m: m_data->range_mineral())
         {
             if (ideq_min(m) == no_equation) continue;
             jacobian(0, ideq_min(m)) = -m_data->nu_mineral(m, 0)/molar_volume_mineral(m);
         }
     }
 }
 
 void AdimensionalSystem::jacobian_aqueous_components(Vector& x, Matrix& jacobian)
 {
     for (index_t i: m_data->range_aqueous_component())
     {
         const index_t idp = ideq_paq(i);
         if (idp == no_equation) continue;
         // Charge balance equation
         // ----------------------
-        if (is_charge_keeper(i))
+        switch (aqueous_component_equation_type(i))
         {
+        case AqueousComponentEquationType::NoEquation:
+            continue;
+        case AqueousComponentEquationType::ChargeBalance:
             // Aqueous components
             for (index_t k: m_data->range_aqueous_component())
             {
                 const index_t idc = ideq_paq(k);
                 if (idc == no_equation) continue;
                 scalar_t tmp_drdb = 0.0;
                 if (m_data->charge_component(k) != 0.0)
                      tmp_drdb = m_data->charge_component(k);
                 // Secondary species
                 for (index_t j: m_data->range_aqueous())
                 {
                     if (   not is_aqueous_active(j)
                         or m_data->nu_aqueous(j, k) == 0.0
                         or m_data->charge_aqueous(j) == 0.0
                         )
                         continue;
                     scalar_t tmp_value = m_data->nu_aqueous(j, k)*m_data->charge_aqueous(j);
                     tmp_value *= secondary_molality(j)/component_molality(x, k);
                     tmp_drdb += tmp_value;
                 }
                 jacobian(idp, idc) += component_molality(x,k)*log10*tmp_drdb;
             }
-        }
+            break;
         // Mass balance equation
         // ---------------------
-        else
-        {
+        default:
             const scalar_t conc_w = density_water()*saturation_water(x);
             // Aqueous components
             for (index_t k: m_data->range_aqueous_component())
             {
                 if (ideq_paq(k) == no_equation) continue;
                 scalar_t tmp_iip = 0;
                 if (k == i) tmp_iip -= component_molality(x, i)*log10;
                 for (index_t j: m_data->range_aqueous())
                 {
                     tmp_iip -= log10*m_data->nu_aqueous(j, i)*m_data->nu_aqueous(j, k)*secondary_molality(j);
                 }
                 jacobian(idp, ideq_paq(k)) = conc_w*tmp_iip;
             }
             // Minerals
             for (index_t m: m_data->range_mineral())
             {
                 if (ideq_min(m) == no_equation) continue;
                 jacobian(idp, ideq_min(m)) = - m_data->nu_mineral(m, i)/molar_volume_mineral(m);
             }
             // Water
             if (ideq_w() != no_equation)
             {
                 scalar_t tmp_iw = -component_molality(x, i);
                 for (index_t j: m_data->range_aqueous())
                 {
                     if ( m_data->nu_aqueous(j, i) == 0 ) continue;
                     tmp_iw -= m_data->nu_aqueous(j, i)*secondary_molality(j);
                 }
                 jacobian(idp, ideq_w()) = density_water()*tmp_iw;
             }
         }
     }
 }
 
 void AdimensionalSystem::jacobian_minerals(Vector& x, Matrix& jacobian)
 {
     for (index_t m: m_data->range_mineral())
     {
         const index_t idm = ideq_min(m);
         if (idm == no_equation) continue;
         for (index_t i: m_data->range_aqueous_component())
         {
             if (ideq_paq(i) == no_equation) continue;
             jacobian(idm, ideq_paq(i)) = -m_data->nu_mineral(m, i);
         }
     }
 }
 
 void AdimensionalSystem::set_secondary_variables(const Vector& x)
 {
     set_saturation_gas_phase(x);
     set_pressure_fugacity(x);
     set_secondary_concentration(x);
     compute_log_gamma(x);
 }
 
 void AdimensionalSystem::set_saturation_gas_phase(const Vector& x)
 {
     m_saturation_gas = saturation_water(x) - sum_saturation_minerals(x);
 }
 
 void AdimensionalSystem::set_pressure_fugacity(const Vector& x)
 {
     for (index_t k: m_data->range_gas())
     {
         if (not is_active_gas(k)) continue;
         scalar_t logp = m_data->logk_gas(k);
         for (index_t i: m_data->range_aqueous_component())
         {
             if (m_data->nu_gas(k, i) == 0.0) continue;
             logp += m_data->nu_gas(k, i) * (log_component_molality(x, i) + log_gamma_component(i));
         }
         m_gas_fugacity(k) = pow10(logp);
     }
 }
 
 void AdimensionalSystem::set_secondary_concentration(const Vector& x)
 {
     for (index_t j: m_data->range_aqueous())
     {
         if (not is_aqueous_active(j))
         {
             m_secondary_conc(j) = 0;
             continue;
         }
         scalar_t logconc = -m_data->logk_aqueous(j) - m_loggamma(j+m_data->nb_component);
         for (index_t k: m_data->range_aqueous_component())
         {
             if (m_data->nu_aqueous(j, k) == 0) continue;
             logconc +=  m_data->nu_aqueous(j, k)*(log_component_molality(x, k) + m_loggamma(k));
         }
         m_secondary_conc(j) = pow10(logconc);
     }
 }
 
 void AdimensionalSystem::set_ionic_strength(const Vector& x)
 {
     scalar_t ionic = 0;
     for (index_t i: m_data->range_aqueous_component())
     {
         if (ideq_paq(i) == no_equation or m_data->charge_component(i) == 0) continue;
         ionic += component_molality(x, i)*std::pow(m_data->charge_component(i),2);
     }
     for (index_t j: m_data->range_aqueous())
     {
         if (not is_aqueous_active(j) or m_data->charge_aqueous(j) == 0) continue;
         ionic += secondary_molality(j)*std::pow(m_data->charge_aqueous(j),2);
     }
     ionic_strength() = ionic/2;
 }
 
 void AdimensionalSystem::compute_log_gamma(const Vector& x)
 {
     set_ionic_strength(x);
     const scalar_t sqrti = std::sqrt(ionic_strength());
     for (index_t i: m_data->range_aqueous_component())
     {
         if (ideq_paq(i) == no_equation)
         {
             log_gamma_component(i) = 0.0;
             continue;
         }
         log_gamma_component(i) = laws::extended_debye_huckel(
                     ionic_strength(), sqrti,
                     m_data->charge_component(i),
                     m_data->a_debye_component(i),
                     m_data->b_debye_component(i)
                     );
     }
     for (index_t j: m_data->range_aqueous())
     {
         if (not is_aqueous_active(j))
         {
             log_gamma_secondary(j) = 0.0;
             continue;
         }
         log_gamma_secondary(j) = laws::extended_debye_huckel(
                     ionic_strength(), sqrti,
                     m_data->charge_aqueous(j),
                     m_data->a_debye_aqueous(j),
                     m_data->b_debye_aqueous(j)
                     );
     }
 }
 
 bool AdimensionalSystem::hook_start_iteration(const Vector& x, scalar_t norm_residual)
 {
     if (not get_options().non_ideality) return true;
 
     not_in_linesearch = true;
     scalar_t previous_norm  = m_loggamma.norm();
     bool may_have_converged = false;
     if (norm_residual < nb_free_variables())
     {
         // Use fixed point iterations for non-ideality
         for (int i=0; i<get_options().non_ideality_max_iter; ++i)
         {
             set_secondary_variables(x);
             compute_log_gamma(x);
             // convergence check
             if (std::abs(previous_norm - m_loggamma.norm())/previous_norm <
                     get_options().non_ideality_tolerance) {
                 may_have_converged = true;
                 break;
             }
             previous_norm = m_loggamma.norm();
         }
     }
     return may_have_converged;
 }
 
 double AdimensionalSystem::max_lambda(const Vector& x, const Vector& update)
 {
     if (ideq_w() != no_equation)
     {
         return 1.0/std::max(1.0, -update(0)/(get_options().under_relaxation_factor*x(0)));
     }
     else
     {
         return 1.0;
     }
 }
 
 void AdimensionalSystem::reasonable_starting_guess(Vector &x)
 {
     x.resize(m_data->nb_component+ m_data->nb_mineral);
     x(0) = 1.0;
     for (index_t i: m_data->range_aqueous_component())
     {
         x(i) = -4.0;
     }
     x.block(m_data->nb_component, 0, m_data->nb_mineral, 1).setZero();
 
     m_loggamma.setZero();
     m_secondary_conc.setZero();
 }
 
 void AdimensionalSystem::reasonable_restarting_guess(Vector& x)
 {
     x(0) = 0.5;
     for (index_t i: m_data->range_aqueous_component())
     {
         if (x(i) > 0 or x(i) < -9)
             x(i) = -3;
     }
     x.segment(m_data->nb_component, m_data->nb_mineral).setZero();
     m_loggamma.setZero();
     m_secondary_conc.setZero();
 }
 
 AdimensionalSystemSolution AdimensionalSystem::get_solution(const Vector& xtot, const Vector& x)
 {
     double previous_norm = m_loggamma.norm();
     set_saturation_gas_phase(x);
     set_pressure_fugacity(x);
     set_secondary_concentration(x);
     if (get_options().non_ideality)
     {
         compute_log_gamma(x);
         if (std::abs(previous_norm - m_loggamma.norm()) > 1e-6)
         {
             WARNING << "Activity coefficient have not converged !" << std::endl
                     << "output can not be trusted\n Difference : "
                        +std::to_string(std::abs(previous_norm - m_loggamma.norm()));
         }
     }
     return AdimensionalSystemSolution(xtot, m_secondary_conc, m_loggamma, m_ionic_strength);
 }
 
 void AdimensionalSystem::reduce_mineral_problem(Vector& true_var)
 {
     for (index_t mineral: m_data->range_mineral())
     {
         if (ideq_min(mineral) == no_equation) continue;
         if (m_data->stability_mineral(mineral) == database::MineralStabilityClass::cannot_dissolve)
         {
             if (true_var(ideq_min(mineral)) == 0.0) continue;
             for (index_t component: m_data->range_component())
             {
                 if (m_data->nu_mineral(mineral, component) == 0.0) continue;
                 m_tot_conc(component) -= m_data->nu_mineral(mineral, component)*true_var(ideq_min(mineral));
             }
             true_var(ideq_min(mineral)) = 0.0;
         }
     }
 }
 
 void AdimensionalSystem::reset_mineral_system(Vector& true_var, Vector& output_var)
 {
     for (index_t mineral: m_data->range_mineral())
     {
         if (ideq_min(mineral) == no_equation) continue;
         if (m_data->stability_mineral(mineral) == database::MineralStabilityClass::cannot_dissolve)
         {
             output_var(mineral) += true_var(ideq_min(mineral));
         }
     }
 }
 
 } // end namespace specmicp
diff --git a/src/specmicp/adimensional/adimensional_system.hpp b/src/specmicp/adimensional/adimensional_system.hpp
index f69543f..4e50eec 100644
--- a/src/specmicp/adimensional/adimensional_system.hpp
+++ b/src/specmicp/adimensional/adimensional_system.hpp
@@ -1,349 +1,356 @@
 /*-------------------------------------------------------
 
  - Module : specmicp
  - File : adimensional_system.hpp
  - Author : Fabien Georget
 
 Copyright (c) 2014, Fabien Georget <fabieng@princeton.edu>, Princeton University
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:
     * Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
     * Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.
     * Neither the name of the Princeton University nor the
       names of its contributors may be used to endorse or promote products
       derived from this software without specific prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 ---------------------------------------------------------*/
 
 #ifndef SPECMICP_ADIMENSIONALSYSTEM_HPP
 #define SPECMICP_ADIMENSIONALSYSTEM_HPP
 
 //! \file reduced_system.hpp The MiCP program to solve speciation
 
 #include "common.hpp"
 #include "database.hpp"
 #include "micpsolver/micpprog.hpp"
 #include "../simulation_box.hpp"
 #include "physics/units.hpp"
 #include "utils/options_handler.hpp"
 
 #include "adimensional_system_structs.hpp"
 
 //! \namespace specmicp main namespace for the SpecMiCP solver
 namespace specmicp {
 
 class AdimensionalSystemSolution;
 
 //! \brief The equilibrium speciation problem
 //!
 //! Represent the equilibrium speciation problem as a Mixed Complementarity program
 //! It is called reduced becaused it does not solve explicitely for the secondary species.
 //!
 class AdimensionalSystem :
         public micpsolver::MiCPProg<AdimensionalSystem>,
         public OptionsHandler<AdimensionalSystemOptions>,
         public units::UnitBaseClass
 {
 public:
     //! \brief Create a reduced system
     //!
     //! \param ptrthermo Shared pointer to the thermodynamic data
     //! \param totconc Vector containing the total concentrations (in mol/volume) for each components
     AdimensionalSystem(
             RawDatabasePtr ptrdata,
             const Vector& total_concentration,
             const AdimensionalSystemOptions& options=AdimensionalSystemOptions()
             );
 
     AdimensionalSystem(
             RawDatabasePtr ptrdata,
             const Vector& totconc,
             const AdimensionalSystemSolution& previous_solution,
             const AdimensionalSystemOptions& options=AdimensionalSystemOptions()
             );
 
     // Variables
     // ==========
 
     //! \brief Return the total number of variables
     index_t total_variables() const {return m_nb_tot_vars;}
     //! \brief Return the number of 'free' variables (not subject to complementarity conditions)
     index_t nb_free_variables() const {return m_nb_free_vars;}
     //! \brief Return the number of variables subjected to the complementarity conditions
     index_t nb_complementarity_variables() const {return m_nb_compl_vars;}
 
     // The linear system
     // ==================
 
     //! \brief Return the residual for the water conservation equation
     scalar_t residual_water(const Vector& x) const;
     //! \brief Return the residual for the conservation equation of component (i)
     //!
     //! For (i==0), water use the method : 'residual_water'
     double residual_component(const Vector& x, index_t i) const;
     //! \brief Equilibrium condition for the minerals \f$ 1 - \mathrm{SI}_l \f$
     double residual_mineral(const Vector& x, index_t m) const;
     //! \brief Charge conservation
     double residual_charge_conservation(const Vector& x) const;
 
     //! \brief Return the residuals
     void get_residuals(const Vector& x, Vector& residual);
     //! \brief Return the jacobian
     void get_jacobian(Vector& x,
                       Matrix& jacobian);
 
 
     // Getters
     // #######
 
     // Equation id access
     // ==================
 
     //! \brief Return the equation id
     index_t ideq(index_t i) const {return m_ideq[i];}
     //! \brief Return the equation number for conservation of water
     index_t ideq_w() const {return m_ideq[0];}
     //! \brief Return the equation number of component 'i'
     index_t ideq_paq(index_t i) const {
         specmicp_assert(i < m_data->nb_component);
         return m_ideq[i];
     }
     //! \brief Return the equation number of mineral 'm'
     index_t ideq_min(index_t m) const {
         specmicp_assert(m < m_data->nb_mineral);
         return m_ideq[m+m_data->nb_component];
     }
 
+    //! \brief Return the type of equation for aqueous species 'component'
+    AqueousComponentEquationType aqueous_component_equation_type(index_t component) const {
+        specmicp_assert(component >= 0 and component < m_data->nb_component);
+        return m_aqueous_component_equation_type[component];
+    }
+
     // Variables
     // =========
 
     // Primary
     // -------
 
     //! \brief Return the saturation of water
     scalar_t saturation_water(const Vector& x) const;
     //! \brief Return the density of water
     scalar_t density_water() const;
     //! \brief Return the saturation (mol/volume) of a mineral
     scalar_t saturation_mineral(const Vector& x, index_t mineral) const;
     //! \brief Return the volume of minerals
     scalar_t molar_volume_mineral(index_t mineral) const;
     //! \brief Return the sum of saturation of the minerals
     scalar_t sum_saturation_minerals(const Vector& x) const;
     //! \brief Return the log_10 of component concentration
     scalar_t log_component_molality(const Vector& x, index_t component) const
     {
         specmicp_assert(ideq_paq(component) != no_equation and component < m_data->nb_component);
         return x(ideq_paq(component));
     }
     //! \brief Return  the concentration of 'component'
     scalar_t component_molality(const Vector& x, index_t component) const
     {
         return pow10(log_component_molality(x, component));
     }
 
     // Secondary
     // ---------
 
     //! \brief Return the concentration of secondary specis 'aqueous'
     scalar_t secondary_molality(index_t aqueous) const
     {
         if (not m_active_aqueous[aqueous]) return 0.0;
         return m_secondary_conc(aqueous);
     }
     //! \brief Return true if 'aqueous' is active
     //!
     //! i.e. Return true if all its component are present in the system
     bool is_aqueous_active(index_t aqueous) const
     {
         return m_active_aqueous[aqueous];
     }
     //! \brief Return log_10(γ_i) where i is a component
     scalar_t log_gamma_component(index_t component) const {
         return m_loggamma(component);
     }
     //! \brief Return log_10(γ_j) where j is a secondary aqueous species
     scalar_t log_gamma_secondary(index_t aqueous) const {
         return m_loggamma(m_data->nb_component + aqueous);
     }
     //! \brief Return the ionic strength
     scalar_t ionic_strength() const {
         return m_ionic_strength;
     }
     //! \brief Return the total concentration of 'component'
     scalar_t total_concentration(index_t component) const {return m_tot_conc(component);}
 
     //! \brief Return the fugacity of 'gas'
     scalar_t gas_fugacity(index_t gas) const {
         return m_gas_fugacity(gas);
     }
     //! \brief Return true if gas is active
     bool is_active_gas(index_t gas) const {
         return m_active_gas[gas];
     }
 
     //! \brief Return the saturation of the gas phase
     scalar_t saturation_gas_phase() const {
         return m_saturation_gas;
     }
 
     //! \brief Return the gas pressure
     scalar_t gas_total_pressure() const {
         return 1.01325e5;
     }
     //! \brief Return the temperature
     scalar_t temperature() const {
         return 273.16+25;
     }
 
 
     // Equilibrium State
     // =================
 
     //! \brief Return the equilibrium state of the system, the 'Solution' of the speciation problem
     AdimensionalSystemSolution get_solution(const Vector& xtot, const Vector& x);
 
 
     // Algorithm
     // #########
 
     //! \brief Compute the ionic strength
     void set_ionic_strength(const Vector& x);
     //! \brief Compute the activity coefficients
     void compute_log_gamma(const Vector& x);
 
     // For the normal algorithm
     void set_secondary_concentration(const Vector& x);
     //! \brief Compute the secondary variables
     void set_secondary_variables(const Vector& x);
     //! \brief Set the gas phase saturation
     void set_saturation_gas_phase(const Vector& x);
     //! \brief Set the fugacity pressure
     void set_pressure_fugacity(const Vector& x);
 
     //! \brief Compute the activity model, called by the solver at the beginning of an iteration
     bool hook_start_iteration(const Vector &x, scalar_t norm_residual);
 
     //! \brief Return a scale factor to avoid negative mass during Newton's iteration
     double max_lambda(const Vector &x, const Vector &update);
     //! \brief Return the component that does not exist in the solution (inactive dof)
     const std::vector<index_t>& get_non_active_component() {return m_nonactive_component;}
 
     //! \brief A reasonable (well... maybe...) starting guess
     void reasonable_starting_guess(Vector& x);
     //! \brief A reasonable (maybe...) restarting guess
     void reasonable_restarting_guess(Vector& x);
 
     //! \brief Reduce the mineral system if one cannot dissolve
     void reduce_mineral_problem(Vector& true_var);
     //! \brief Reset the mineral system to the true problem
     void reset_mineral_system(Vector& true_var, Vector& output_var);
 
     //! \brief set the charge keeper to 'component'
     //!
     //! The equation for the charge keeper is replaced by the charge balance
     //!
     //! Set component to 'no_species' to solve charge conservation implicitely.
     //! In this case, the total concentration must conserve the charge.
     void set_charge_keeper(index_t component)
     {
         specmicp_assert(component >= 1 and component < m_data->nb_component);
         get_options().charge_keeper = component;
     }
 
     //! \brief Return true if 'component' is thecharge keeper
     bool is_charge_keeper(index_t component)
     {
         return (    get_options().charge_keeper != no_species
                 and component == get_options().charge_keeper
                 );
     }
 
 // Private Members and attributes
 // ##############################
 private:
 
     // Jacobian
     // ########
 
     void jacobian_water(Vector& x, Matrix& jacobian);
     void jacobian_aqueous_components(Vector& x, Matrix& jacobian);
     void jacobian_minerals(Vector& x, Matrix& jacobian);
 
     // Equation numbering
     // ##################
 
     void number_eq();
 
     // Setter
     // ######
 
     // main variables
     // --------------
 
     // they are set by the solver
 
     // Secondary variables
     // -------------------
 
     //! \brief Return a reference to log_10(γ_i) where i is a component
     scalar_t& log_gamma_component(index_t component) {
         return m_loggamma(component);
     }
     //! \brief Return a reference to log_10(γ_j) where j is a secondary aqueous species
     scalar_t& log_gamma_secondary(index_t aqueous) {
         return m_loggamma(m_data->nb_component + aqueous);
     }
     //! \brief Return a reference to the ionic strength
     scalar_t& ionic_strength() {
         return m_ionic_strength;
     }
 
     // Attributes
     // ##########
 
     RawDatabasePtr m_data;
     Vector m_tot_conc;
 
     index_t m_nb_tot_vars;
     index_t m_nb_free_vars;
     index_t m_nb_compl_vars;
 
     std::vector<index_t> m_ideq;
+    std::vector<AqueousComponentEquationType> m_aqueous_component_equation_type;
 
     Vector m_secondary_conc;
 
     Vector m_loggamma;
     scalar_t m_ionic_strength;
 
     scalar_t m_saturation_gas;
     Vector m_gas_fugacity;
 
     bool not_in_linesearch;
 
     std::vector<index_t> m_nonactive_component;
     std::vector<bool> m_active_aqueous;
     std::vector<bool> m_active_gas;
 
 };
 
 } // end namespace specmicp
 
 
 #endif // SPECMICP_ADIMENSIONALSYSTEM_HPP
diff --git a/src/specmicp/adimensional/adimensional_system_structs.hpp b/src/specmicp/adimensional/adimensional_system_structs.hpp
index ebe1b61..8364fd4 100644
--- a/src/specmicp/adimensional/adimensional_system_structs.hpp
+++ b/src/specmicp/adimensional/adimensional_system_structs.hpp
@@ -1,30 +1,42 @@
 #ifndef SPECMICP_SPECMICP_ADIMENSIONALSYSTEMSTRUCTS_HPP
 #define SPECMICP_SPECMICP_ADIMENSIONALSYSTEMSTRUCTS_HPP
 
 #include "common.hpp"
 
 namespace specmicp {
 
+//! \brief Options for the Adimensional Systems
 struct AdimensionalSystemOptions
 {
     bool conservation_water; //!< Solve the conservation of water
     index_t charge_keeper;   //!< Index of species used for charge balance
     bool non_ideality;       //!< Solve for non ideality
     scalar_t non_ideality_tolerance; //!< Tolerance for non ideality
     index_t non_ideality_max_iter;  //!< Max iterations fornon ideality
     scalar_t under_relaxation_factor; //!< Under relaxation factor for the conservation of water
 
 
     AdimensionalSystemOptions():
         conservation_water(true),
         charge_keeper(no_species),
         non_ideality(true),
         non_ideality_tolerance(1e-8),
         non_ideality_max_iter(10),
         under_relaxation_factor(0.9)
     {}
 };
 
+//! \brief Type of an aqueous component equation
+enum class AqueousComponentEquationType
+{
+    NoEquation,         //!< Not an equation, component is not present in the system
+    MassConservation,   //!< Mass balance
+    ChargeBalance,      //!< M.B. replaced by charge balance
+    FixedFugacity,      //!< M.B. replaced by a fixed fugacity equation
+    FixedActivity       //!< M.B. replaced by a fixed activity equation
+};
+
+
 } // end namespace specmicp
 
 #endif // SPECMICP_SPECMICP_ADIMENSIONALSYSTEMSTRUCTS_HPP