Every week night (not Saturday and Sunday) a stored procedure is scheduled to run to backup our SQL Server database "Altek". Altek.mdf is about 5 GB. The stored procedure uses the BACKUP DATABASE statement to create a .bak file. The backup files have been about 3.8 GB for months. Last week on Monday night the backup file was approximately 7.7GB, then it went back down to 3.8 GB every week night for the rest of the week. Now, again last night (Monday night) the backup file went back up to 7.7GB. What could cause the backup file to be twice as big on certain nights?