Recently, there has been a lot of talk on MASA about the redfields ratio (ratio of nitrogen, phosphorus & carbon in planctonic creatures). Ive always followed redfield discussions out of curiosity, but only this week i finally got a glimpse of what its all about (or at least a part of it). Ive always been a fan of low nutrient systems & always tried to keep my tank's nutrients as low as possible for 2 reasons: 1. algae control 2. Sps coral colors Ever since i started my latest tank, my phosphates has always been very low (+-0.01) but ive always had some nitrates (around 2-4ppm). I could never understand why i cant get my nitrates below 1ppm... About 3 weeks ago, i added Orca nitra-guard biocubes (fantastic product) to my tank. The effect was that my nitrates dropped from 4ppm to 2ppm in one week & phosphates from 0.01-undetectable even on a professional test kit. My problem is this... my nitrates seem to have stabilized at 2ppm even with the biocubes in my tank & doesn't seem to get lower than that no matter what!!! My question: Can it be that the absence of phosphorus (phosphates) in my tank is prohibiting the bacteria's ability to absorb (convert) any more nitrates because of the imbalance in redfields ratio & if so, 1. How can i overcome this barrier in my nitrate level? 2. Is this a common finding in low nutrient systems? 3. Do i need to increase the phosphates to balance the ratio?(preferably dont want to try this...) 4. Is it possible with the newer Nitra-guard titanium to overcome similar redfield ratio problems? Any advice would be greatly appreciated!!! Thanks guys!