I would 50% water changes everyweek and maybe a 20% water change aswell in between the 50%. (thats what I did when I had a bacterial bloom and my water cleared up in 2 weeks or so.) Just make sure you dont Vaccum the gravel more than twice a week so you dont loose alot of bio-bugs. So What I would do is Vaccum the gravel when your doing the 20% water change and when you do the 50% water change, just take out water and dont mess with the gravel.