Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_28019988_5 (season__number INTEGER, us_viewers__million_ VARCHAR, written_by VARCHAR)

### Question ###
What episode number of the season was written by Tom Garrigus and had 2.31 million u.s. viewers?

### Accurate SQL ###

SELECT MAX(season__number) FROM table_28019988_5 WHERE us_viewers__million_ = "2.31" AND written_by = "Tom Garrigus"