I think Detritus is a combination of several different types of organic matter. Like bodies or fragments of dead organisms, fecal material, and old food that piles up in ur sump, overflow box, under your rock work, or in cracks and crevices on the rock itself. All this organic matter will start decomposing if not siphoned out. As a result, this will affect ur water Chemistry. A couple examples that instantly come to my mind are elevated NO3 and PO4 levels. This is why a lot of SPS fanatics run low nutrient systems. If ur corals are trying to live and grow in high NO3 and PO4, it can irritate or even stunt the growth of some SPS.
However, stripping the water column completely isn't good either. I've experienced both. You need some PO4 in the water. Since I've been running my tank around 10 ppb or 0.03 ppm, I've had less issues with all my anemones. I'm actually running at 0.02 ppm as we speak. Typically, this is lower than I would normally like to run, but I'm killing some GHA right now.
Most people would be shocked if they knew how high their Phosphate levels are. This is because most people don't test often, but they'll tell you they do. I think everybody should own the Hanna Phosphorus ULR (Ultra Low Range) checker. IMO, it's a good way to accurately measure ur PO4 levels. I don't like the other tests.
