nitrate removal ?

Tyyrlym

Yeah, it says to do that tumbling motion for a minute. I shake the piss out of it for about twenty seconds. I figure if its not stirred up by then it never will be.

Oldman47

If you don't do at least the full minute you will tend to get lower than actual readings. There is no point in testing if you won't do it right.
As all the others have already said, nitrates are best controlled with water changes but plants can go a long way to controlling nitrates completely. I have 2 of my planted tanks that I add nitrates to for plant food, the fish do not produce enough to feed them. They are rather heavily planted but they need more nitrogen than the fish provide. That could be why you only see 10 ppm no matter what.