Nitrates don't ussually spike unless something dies. They build up depending on the bio load and decaying matter in you tank. The most effective way of removing them is with water changes. Now if you meant NITRITES; that is part of the Amonia\Nitrite cycle for starting a new tank with 100% new water. If you already have a tank and want to set up another one, you could use some if not all of the water from your old one at your next water change. This will bring over benifical bacteria that would speed up the cycling process. I hope this helps.

BTW: Welcome to Maast.

-SoLiD