Black mass?

[Zoe Horsfield]

No, carbon relates to KH which is less important for the fish. GH is the levels of magnesium and calcium minerals and there are some in the Yorkshire water. I am told goldfish can adapt to a range of GH levels and trying to change this aspect of water chemistry is not advised.
My reason for the question was in case you had a water softener which may replace calcium and magnesium with sodium. This could effect a fish's health. Hopefully your fish just has natural colouration causing the dark patch. Goldfish commonly change colour.

Ah right thank you, I was worried it may be like compaction of faeces which I Imagine wouldn’t be very comfortable but it doesn’t seem swollen or anything and is probably just a reflection off the scales

 

[Essjay]

Your hardness converts to 5.3 dH and 95 ppm; those are the two units you'll find in fish profiles.





Just a quick comment about the difference between the figure given under hardness as mg/l calcium and the figure given for calcium in the water quality report. They are not the same thing.

Hardness is the amount of calcium and magnesium and some other metals in trace amounts. They can't say "hardness is x mg/l calcium and y mg/l magnesium and z mg/l something else" so they treat it as if all the hardness minerals were just one thing. In Yorkshire Water's case, the hardness figure is what it would be if all the hardness minerals were calcium. Other companies give it as though all the hardness minerals were calcium carbonate.

The figure for calcium in the water quality report is the amount of just calcium.

[My younger son used to work as an analyst for a water testing company and he explained it]

 

[Zoe Horsfield]

Your hardness converts to 5.3 dH and 95 ppm; those are the two units you'll find in fish profiles.





Just a quick comment about the difference between the figure given under hardness as mg/l calcium and the figure given for calcium in the water quality report. They are not the same thing.

Hardness is the amount of calcium and magnesium and some other metals in trace amounts. They can't say "hardness is x mg/l calcium and y mg/l magnesium and z mg/l something else" so they treat it as if all the hardness minerals were just one thing. In Yorkshire Water's case, the hardness figure is what it would be if all the hardness minerals were calcium. Other companies give it as though all the hardness minerals were calcium carbonate.

The figure for calcium in the water quality report is the amount of just calcium.

[My younger son used to work as an analyst for a water testing company and he explained it]

Thank you