Crap!!! :thumbdown: my tapwater contains:
permanent hardness: 3,8 °dH
carbonat hardness: 16,5 °dH
total hardness: 20,1 °dH
Well, that explains why I always fail! And RO water isn't an option since I haven't found a RO unit big enough and afordable to use for my 325 l. tank! :cry: But thanks for...