Constant nitrate issues

I have a 300L freshwater tank which I've had for about 2 years, and I've always had issues with nitrate levels. My nitrate level is always around 160ppm. I try and feed lightly.
I've read multiple forums and spoken to a few different fish shops and nearly all of them have said just do more frequent water changes. I currently do a 30% change once a week.

I know that I do not have to get my nitrate down to 0 but I'm struggling to get it down at all.
A fish pal of mine recently gave me his canister filter to run along my current canister filter to try and help reduce it.

One of the people I was talking to highly recommended putting MarinePure and a Poly-filter pad in my filter. Has anyone had any experience with these two products and had success?