Hello Board, I live in London, to those of you not in London that means limescale on EVERYTHING, alkaline tapwater (average 7.9 but generally around 8.3) and a hardness of 200-300mg/L total. This does not lend itself to beautiful fish (although all the shops keep their stock in tapwater) and I have started using RO water mixed 70: 30 with tapwater, this has lowered the pH to about 7.4 (it will prob. not get much lower) and the hardness is coming down. My stock is some harlequin rasboras, black neons, celestial pearl danios and pakistani loaches, some echinodorus and aponogenton plants and a bit of floating Salvinia to give the fish some cover which they live, no CO2 but an LED light to keep the tank bright. At the moment I am doing 30% water changes a week, costing me Â£2.25 in RO which does add up, Are there any fish suitable for such hard water- I was hoping to keep lampeyes and swordtails in London tapwater, would this work? Swapping the plants for vallis I guess.