Look up the Argo project, ...

Look up the Argo project, which has  many operation CTD  floats operating off the coast of Mozambique,  you can plot these on google earth and get many months of data in public domain , the argo probes  give very accurate salinity measurement  in PSU and surface temperature.  This is the most important first data.  if you have no data on turbidity and suspended solids, then assume its bad and  use a lamella clarifier as first step for pretreatment  with a bypass (if turbidity is in reality low).  IF algae bloom not a likely issue (i would not expect it there) then dont use DAF .  I suggest deep bed gravity DMF with  1.5m of pumice or filtralite over  0.7m sand as pretreatment, this will prevent  major biofouling of the RO (pumice and filtralite are excellent  biological filters). Do not cover DMF , do not chlorinate DMF filters,  Do not use UF/MF (nigthmares for RO biofouling)  . Use pigging (eg Pigteck) for intake lines (use 2)  instead of  shock chlorination  (far cheaper and far more effective, and no  biofouling impact from  dechlorinated organics on RO ).   That is fast guide .