Product Website: Aquaripure I've seen mention of this device several times on forums. I thought I would take a few moments to give you my perspective, as these filters are not cheap and I assume a variety of people have bought one. If you want to save your time reading this entire post, My advice as long time aquarist, aquarium writer and consultant, is DO NOT BUY ONE. If you continue reading, I will explain why. The aquari-pure is basically a biological de-nitrator. Inside the canister is a filter media that encourages the colonization of anaerobic bacteria, which consume a carbon source and breakdown nitrates into CO2. According to the manufacturer the media within the aquari-pure never requires changing. The filter comes sealed, with a label warning that if it is ever opened any warranty is voided. Overall it's a simple enough device, an inlet hose is powered by a small cobalt powerhead, with an outflow that can be positioned anywhere on an aquarium wall or sump. There is a dosing port on the filter's top, where a carbon source is injected, feeding the population of anaerobic bacteria. Now to the bad news. Like any de-nitrator, the aquari-pure must cycle. This takes several weeks. Every three days the system must be dosed with a carbon source. The manufacturer provided source is a liquid, very similar to Red Sea's Nitrate and Phosphate reducer. When fully cycled and operating normally, the aquari-pure does lower nitrates, often taking them down to zero. The issue arises when the filter constantly de-cycles. Over the course of the nearly two (2) years I had an aquari-pure, the system would de-cycle monthly, and nitrates within the affluent would rise to well over 70 ppm. I never could determine the cause of the de-cycle, as the flow rate was set to manufacturer recommendation and I was following the dosing schedule, using the provided liquid. When it does work properly, the output tubing quickly clogs up with a white, slimy bacteria film, and the entire unit has to be shut down and the tube cleaned with a pipe cleaner. The short shut down period typically causes the filter to de-cycle, releasing high nitrate into the tank for several weeks unit the bacteria has replenished. If the filter is working correctly it often leaches a strong rotten egg stench, making the room the tank is in smell badly. This rotten egg smell is sulfur, often produced by de-nitrifying bacteria, though the filter is not equipped with anything to absorb the smell, allowing it to "stink up" the surrounding space for a matter of hours or days. If you leave on a trip and can't dose the tank every three (3) days, it will de-cycle and you will return to a nitrate filled aquarium. Based on my experience and the ridiculously high price tag, I would rate the aquari-pure as one of the poorest aquarium products I've encountered in terms of both cost and performance.