This is true on one level, I spend a large proportion of my time trying to reduce eutrophication of natural ecosystems. The whole environment is awash with unnatural levels of nitrogen and phosphorus, and it is a major cause of environmental degradation. Phosphate stripping, using Fe(II) ammonium sulphate as a precipitant (this is very effective removing about 95% of the phosphate), was introduced to deal with problems caused by optical brighteners in detergents, sewage etc. The orthophosphate (PO4---) ion naturally limits productivity (along with NO3-) in many aquatic systems. Add non-limiting amounts of PO4--- creates huge blooms of planktonic green algae (Chlorophyta) "Green water", which then die of in the autumn as PAR (photosynthetically active radiation) and temperature decline. This decay adds a huge amount of biochemical oxygen demand (BOD) to the water, de-oxygenating it, killing and/or altering its biota. Once the phosphate is present in the ecosystem it remains bound to clays (they have AEC - Anion Exchange Capacity), and as largely insoluble phosphate compounds, and this reservoir will then supply enough PO4--- (orthophosphate ions) to repeat the whole process again and again. But, it isn't applicable to aquaria. The levels of phosphorus in an aquarium will always be high enough to support algal growth, unless we take extreme measures (100% total RO water changes, chemical adsorption) to remove it.