I simulate a seawater intrusion .I open the result form postprocess and check the mass of 250mg/l , the log message says: WARWING:*** ERROR in 'iso 3',(5511>5510)buffer too small! if i  change the 250mg/l into 150mg/l or 300mg/l,the warning disapears.
what does the log mean? how can i do?
any advice is welcome.