table growing

Hi

I have a growing database problem… I insert rows in a table automatically(1500 by hour approx) and I use this table like a temporary table 24/7…All rows inserted are

deleted(maybe 12-24 hours later)but the database grow all the time I tried vacuum,analyze,vacuum full, reindex, max_fsm_pages =100000,1000000 etc…

the only way to reduce space is dump table /drop table/create table and insert after but after 12-24 hours… the table is very big and request are very slow

12G before the drop and 250m after the drop/create/insert…

ideas?

Thanks!

Stephane