Review on 🐟 Sera Siporax Professional 15 mm 1,000 mL, 10.2 oz. Aquarium Filter Accessories: Optimal Filtration for a Crystal-Clear Tank by Clint Blackman

So I bought this a little over a year ago hoping to lower nitrates in my tanks. I can't say whether it worked in the first few months. I stopped testing and forgot about them after 4 months. Now that a year has passed this has reduced the amount of nitrates coming out of the tap from over 10ppm to 0ppm in a day or two depending on how big my water change is. The bacteria needed for denitrification take time, so be patient and wait at least 6 months for them to take root.