Thanks for the response Byron - that being the case, should I be looking to remove these elements (as the recommended water hardness for neon tetras is considerably lower than my reading)?
As the filter has been added it may reduce levels but I don't want to endanger the fish..
New to this and new tank - after weeks of prep, finally have neon tetras in.
Testing the water, all seems fine except for the water hardness, which is measuring at the hardest on the scale (180).
We tested our tap water and this had a very soft measurement (20).
We now have a new tank filter...