These are the two numbers you need. German degrees is the same as dH and mg/l CaCO3 is the same as ppm. Fish profiles use either dH or ppm, and you now have your hardness in both - 253 ppm and 15 dH.Total hardness 253 mg/ I CaCO3
15 degrees German
(The reason I have a reputation for understanding water chemistry is that I have a degree in chemistry, although it was a long time ago now. And my son also has a degree and doctorate in chemistry and used to work as an analyst for a water testing company so I can always ask him
	            
 That's an awesome resource, thank you! Especially since searching "RO water, Bristol" basically gives you links to pretty pricey filters, which I'm not quite ready to invest in! There is a location within a 20-30 minute drive, and the price point is very reasonable. Worth it for the Oto gang. Hmm. Now it opens up possibilties for a large-ish nano tank. The otos with some ember tetras or purple halequin raspboras perhaps? Or celestial pearl danios? (would research hardness and other conditions first of course, just the idea of a softer water tank, since I really have to set one up now, is sparking some ideas!)