Gentlemen, please forgive me if this subject has already been raised, however I can find no mention of it after exhaustive searching. After a lapse of 40 years, since I last attempted to grow Cryptocoryne in the very limited technology of those days, I have maintained a tank using modern principles, including EI, and injected CO2 with some success. Recently a VERY old friend invited me round for a drink, and after some time discovered that he too maintained a plant tank. When I first saw this, I was frankly speechless with admiration, the plants, and especially the Cryptocoryne, were magnificent, huge stands that I have only ever seen in books. He runs a Dennerle system, with injected Co2, and a Deponit substrate, and originally used Dennerle ferts, however he became fed up with the cost of these, and shifted to EI.One day he had no Ei available and decided to try using Phostrogen, he has no fish just plants, and on the basis of what has happened since, has continued to use it with seemingly astounding results. He doses, and I have seen him do this, 'about a quarter teaspoon evey other day', and changes 'about 30/40% of the water every other week. Please Gentlemen, I have read Tom Barr's erudite writings over and over again, and those contained in this site, how is this possible?, I note that most of the Nitrogen in Phostrogen is from Urea and not Ammonium, but is he nurturing a ticking timebomb?, or is my name justified?