Stuart.........I agree with your analysis of the de-ionizer and the $'s. The is a problem with some of the Apisto's and harder water however. Like me for so many, many years they would just exist in my tank and not "turn-on"..............reducing pH and hardness have made these little fish at the top of my list....them and killies.....;-) I gave away spawning discus to make room for the apisto's..........am I stupid or what??? Mike