Turtle clean is great. I used it for years. There is another one called "Biotize" that works great too.
Currently I use one that is more concentrated so I don't have to buy 10,000 bottles of enzyme cleaner (I go thru a lot since I have a 90-gallon tank). I bought it at a salt-water shop, but can't remember the name off hand. I only use a teaspoon of it for my entire 90-gallon tank so it lasts longer (it's also a lot more expensive than turtle clean).
Needless to say, if you go with turtle-clean, you will be fine. You use a capful of the stuff for every 5 gallons of water. Use turtle clean every time you change the filter media. The water may be a bit cloudy for day or two, but it will clear up & be sparkling with no smell for weeks on end.
FYI - I do 100% water change for my 90-gal tank every 4 weeks, just to give you an idea.