SQL SERVER 2008 DATETIME CONVERSION FAILURE

Question

this is giving me an error below , failed conversion, keep in mind the format thats in the database is 'YYYYMMDD:hhmmss' try this value '20111112:000000' can someone assist me


DELETE  
FROM Color
WHERE REPLACE(CONVERT(VARCHAR,Color.CreatedDateTime, 102),'.','/') +' '+ CONVERT(VARCHAR, Color.CreatedDateTime, 108) < (GETDATE()-30)