pH scale

[Balmoral]

No, not this pH, the acid/alkaline one

I am trying to create an animated gauge that shows pH falling from 8.6 to 5.4, there is a needle to show the fall and there are also coloured blocks on the scale.

I am struggling with the colours. If I Google images pH scale, the colours shown are not consistent, with some showing that the full range as detailed above is all green neutral, whilst others show it as an extreme of purple down to red. And all sorts of other colour options, even all white within the range as detailed above.

What are the definitive colours that I should use to show a fall from 8.6 to 5.4?

Or alternatively, what would you recommend?

I am thinking mainly green through a patch of yellow/amber and then just touching on red.

Thanks in advance,

Warren.

[Balmoral]

Thanks for the fast response Alastair, problem is, I Google UI and still they're different!

(Sorry, I'm no chemist)

[Balmoral]

V8LM said:

There is no standard, but if you wish to be 'scientific' about it then pH in water ranges between 0 and 14, so by taking 0 as the far red of the spectrum and 14 as deep violet:

I think we have a winner!

That's not far off what I was thinking myself, I'm dealing with seawater which is neutral (green) and then becoming slightly acidic as the pH drops (through amber and almost but not quite into red).

Thanks everyone for your help.