need help reducing nitrates

[Rougekitten]

I have 2 hob filters, a penguin biowheel 150 with filterfloss and carbon. and an aqueon quite filter 30 with nitrate reducing filter floss and sponge. I've been doing 33%water changes every 10days for 2 months and nitrates wont go down, I have 3 turbo snails and 3 medium sized fish and 1 small damsel in a 30 gallon aquarium with alot of live rock.
nitrates 40ppm

 

[Robertellis30]

When I was trying to drop my nitrates. I did water changes every other day for 2 weeks. At the same time dosing Red Sea NoPox. Went from extremely high to .75 in no time.

 

[W1ngz]

How much are you feeding? There's nothing at all in there to consume the nitrates so I would increase the pace of water changes from 33% every 10 days to 50% weekly.

How high is high? Real numbers make for real answers.