I personally think it is a good think, altho it sort of gave me a tank "crash" in the end. I got a bad flatworm problem due to not looking carefully at the chaeto before adding it to my 29 system. So i'm now in the process of taking that tank down.
anyways, before it, i had 20 nitrates always. I added a small clump to a AC 70 HOB filter. In about 2 weeks i had 0 nitrates, and i've never had nitrates since adding it.