hi im in the process of getting bits together for my discus set up,15 years ago i used only ro with a water conditioner i used to save money as ro right is exspensive,it was 50% marine salt 25% epsom salt and 25% calcium carbonate, i mixed it up in a squash bottle and added when needed i even bread with this method,any one know of any better recipes or use similair,i have seen people useing gypsom? regards paul