diff --git a/cime_config/namelist_definition_blom.xml b/cime_config/namelist_definition_blom.xml
index 14eab238..ff56d14e 100644
--- a/cime_config/namelist_definition_blom.xml
+++ b/cime_config/namelist_definition_blom.xml
@@ -3809,16 +3809,6 @@
     <desc>Switch for M4AGO settling scheme</desc>
   </entry>
 
-  <entry id="leuphotic_cya">
-    <type>logical</type>
-    <category>bgcnml</category>
-    <group>bgcnml</group>
-    <values>
-      <value>.false.</value>
-    </values>
-    <desc>Switch for cyano-bluefix in euphotic zone only</desc>
-  </entry>
-
   <entry id="lkwrbioz_off">
     <type>logical</type>
     <category>bgcnml</category>
diff --git a/hamocc/mo_control_bgc.F90 b/hamocc/mo_control_bgc.F90
index 5bb0042a..c928e4da 100644
--- a/hamocc/mo_control_bgc.F90
+++ b/hamocc/mo_control_bgc.F90
@@ -61,7 +61,6 @@ module mo_control_bgc
   logical           :: do_oalk                = .false. ! apply ocean alkalinization
   logical           :: with_dmsph             = .false. ! apply DMS with pH dependence
   logical           :: use_M4AGO              = .false. ! run with M4AGO settling scheme
-  logical           :: leuphotic_cya          = .true.  ! allow cyanobacteria to grow only in euphotic zone
   logical           :: lkwrbioz_off           = .false. ! if true, allow remin and primary prod throughout full water column
   integer           :: sedspin_yr_s           = -1      ! start year for sediment spin-up
   integer           :: sedspin_yr_e           = -1      ! end   year for sediment spin-up
diff --git a/hamocc/mo_cyano.F90 b/hamocc/mo_cyano.F90
index 93c72970..110b14f7 100644
--- a/hamocc/mo_cyano.F90
+++ b/hamocc/mo_cyano.F90
@@ -49,7 +49,7 @@ subroutine cyano(kpie,kpje,kpke,kbnd,pddpo,omask,ptho)
     use mo_param_bgc,   only: bluefix,rnit,tf0,tf1,tf2,tff
     use mo_param1_bgc,  only: ialkali,iano3,igasnit,iphosph,ioxygen,inatalkali,ianh4
     use mo_biomod,      only: intnfix
-    use mo_control_bgc, only: use_natDIC,leuphotic_cya,use_extNcycle
+    use mo_control_bgc, only: use_natDIC,use_extNcycle
 
     ! Arguments
     integer, intent(in) :: kpie                                          ! 1st dimension of model grid.
@@ -75,7 +75,7 @@ subroutine cyano(kpie,kpje,kpke,kbnd,pddpo,omask,ptho)
     do j=1,kpje
       do i=1,kpie
         if (omask(i,j) > 0.5) then
-          do k=1,merge(kwrbioz(i,j),kmle(i,j),leuphotic_cya) ! if leuphotic_cya=.true., do bluefix only in euphotic zone
+          do k=1,kwrbioz(i,j) ! bluefix only in euphotic zone
             if (ocetra(i,j,k,iano3) < (rnit*ocetra(i,j,k,iphosph))) then
               if (use_extNcycle) then
                 ! assuming nitrate and ammonium required for cyanobacteria growth (as bulk PP)
diff --git a/hamocc/mo_hamocc_init.F90 b/hamocc/mo_hamocc_init.F90
index b43d9460..d52f7b95 100644
--- a/hamocc/mo_hamocc_init.F90
+++ b/hamocc/mo_hamocc_init.F90
@@ -43,7 +43,7 @@ subroutine hamocc_init(read_rest,rstfnm_hamocc)
                               do_sedspinup,sedspin_yr_s,sedspin_yr_e,sedspin_ncyc,                 &
                               dtb,dtbgc,io_stdo_bgc,ldtbgc,                                        &
                               ldtrunbgc,ndtdaybgc,with_dmsph,l_3Dvarsedpor,use_M4AGO,              &
-                              do_ndep_coupled,leuphotic_cya,lkwrbioz_off,do_n2onh3_coupled,        &
+                              do_ndep_coupled,lkwrbioz_off,do_n2onh3_coupled,                      &
                               ocn_co2_type, use_sedbypass, use_BOXATM, use_BROMO,use_extNcycle
     use mo_param1_bgc,  only: ks,init_por2octra_mapping
     use mo_param_bgc,   only: ini_parambgc
@@ -81,7 +81,7 @@ subroutine hamocc_init(read_rest,rstfnm_hamocc)
          &            do_sedspinup,sedspin_yr_s,sedspin_yr_e,sedspin_ncyc,                         &
          &            inidic,inialk,inipo4,inioxy,inino3,inisil,inid13c,inid14c,swaclimfile,       &
          &            with_dmsph,pi_ph_file,l_3Dvarsedpor,sedporfile,ocn_co2_type,use_M4AGO,       &
-         &            leuphotic_cya, do_ndep_coupled,do_n2onh3_coupled,lkwrbioz_off
+         &            do_ndep_coupled,do_n2onh3_coupled,lkwrbioz_off
     !
     ! --- Set io units and some control parameters
     !
diff --git a/hamocc/mo_param_bgc.F90 b/hamocc/mo_param_bgc.F90
index 4d35798d..8deac006 100644
--- a/hamocc/mo_param_bgc.F90
+++ b/hamocc/mo_param_bgc.F90
@@ -37,7 +37,7 @@ module mo_param_bgc
                             do_ndep,do_oalk,do_rivinpt,do_sedspinup,l_3Dvarsedpor,                 &
                             use_BOXATM,use_CFC,use_PBGC_CK_TIMESTEP,                               &
                             use_sedbypass,with_dmsph,use_PBGC_OCNP_TIMESTEP,ocn_co2_type,use_M4AGO,&
-                            leuphotic_cya,do_ndep_coupled,do_n2onh3_coupled,use_extNcycle,         &
+                            do_ndep_coupled,do_n2onh3_coupled,use_extNcycle,                       &
                             lkwrbioz_off
   use mod_xc,         only: mnproc
 
@@ -834,7 +834,6 @@ subroutine write_parambgc()
       call cinfo_add_entry('with_dmsph',             with_dmsph)
       call cinfo_add_entry('do_sedspinup',           do_sedspinup)
       call cinfo_add_entry('l_3Dvarsedpor',          l_3Dvarsedpor)
-      call cinfo_add_entry('leuphotic_cya',          leuphotic_cya)
       call cinfo_add_entry('lkwrbioz_off',           lkwrbioz_off)
       call cinfo_add_entry('use_M4AGO',              use_M4AGO)
       if (use_extNcycle) then