I use Pond Matrix in my sump. It took a while to get going, but once it did I've not been able to get N03 above 2 or 3....lately it's barely been 0.25ppm
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And for reference, before using it I was battling N03
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Not sure if it's the same media as DeNitrate, but it probably is...for some reason the directions for use are a bit different (flowrate). I know Pond Matrix is the same as media as "Matrix", but it is much less expensive. I bought a 4L bucket of Pond Matrix for $26 vs $14 for 500ml of Matrix.
The larger grain size makes it easier to clean. I've keep it in a vegetable bag, and right before I do a water change I turn off the pumps, lift it up, and shake out the detritus.
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All in all, I'm a fan