Hardness - words vs numbers

Essjay · Aug 3, 2020

We always say to look on your water provider's website for hardness, and to ignore any words, look for a number.
These are UK water company definitions of hardness compared to what we consider to be hard, soft and middling in fish keeping.

Always look for numbers

dH	ppm	Water company	Fish keeping
0 – 2.8	0 - 50	soft	very soft
2.8 – 5.6	50 - 100	moderately soft	soft
5.6 – 8.4	100 - 150	slightly hard	soft
8.4 – 11.2	150 - 200	moderately hard	soft to middling
11.2 – 16.8	200 - 300	hard	middling to hard
over 16.8	over 300	very hard	hard to very hard

Salty&Onion · Aug 5, 2020

I personally think this should be in Useful Links section

Retired Viking · Aug 5, 2020

I agree, it would come in handy for new fish keepers and as a good reminder to the more experience fish keepers.

Byron · Aug 5, 2020

Agree as well...Very useful information.

JuiceBox52 · Aug 5, 2020

I agree with everyone else

maybe one of the mods could pin it

utahfish · Aug 5, 2020

Im not sure in the US they categorize ppm or DGH as soft or hard, they just merely give either a ppm number or a DGH number.
Having said that even if one comes to a consensus about what the numbers represent( soft- hard) the general consensus on what fish one can have in those water parameters wildly varies from source to source, which leads to more confusion in and among the hobby.

Essjay · Aug 6, 2020

In the UK, when we search our water company's website for hardness, they always give it in words, and if we are lucky they also give a number.
But the words they use for each band of hardness do not correspond to the words we, as fish keepers, would use for the same numbers. Their words make our water sound harder than we would consider it to be from the numbers.

For example, if the number is 8.5 dH, we would consider that to be suitable for many soft water fish, but the water company would give it as 'moderately hard'. These words could lead the unsuspecting fish keeper to assume they must keep hard water fish.

seangee · Aug 6, 2020

essjay said:
For example, if the number is 8.5 dH, we would consider that to be suitable for many soft water fish, but the water company would give it as 'moderately hard'. These words could lead the unsuspecting fish keeper to assume they must keep hard water fish.

Is that an "agreed" UK wide standard or can the water companies use their own definitions? Would be very useful if it was standardised.

Essjay · Aug 6, 2020

My water company, Northumbrian Water, no longer gives numbers. It used to until the end of last year, and then they also gave a coloured chart showing the bands.

Not all water companies define their hardness bands but the ones that do give the same as the table in the first post:
Yorkshire Water
United Utilities
South West Water

Southern Water has fewer bands so they make it sound worse - moderately hard starts at 100 ppm or 5.6 dH!

Thames Water use a diagram which makes a lot more sense than the bands other companies use

I haven't looked at every water company by any means. Can I ask UK members to check on their water company's website to see if they give a hardness band table.

Wills · Aug 6, 2020

Really useful - I would imagine that the uk uses those phrases for people to consider using things like Calgon in washing machines to protect against limescale. If they said water was soft in the same way we do they would have customers complaining they were not warned if they got limescale build up.

Wills · Aug 6, 2020

essjay said:
My water company, Northumbrian Water, no longer gives numbers. It used to until the end of last year, and then they also gave a coloured chart showing the bands.

Not all water companies define their hardness bands but the ones that do give the same as the table in the first post:
Yorkshire Water
United Utilities
South West Water

Southern Water has fewer bands so they make it sound worse - moderately hard starts at 100 ppm or 5.6 dH!
View attachment 111951

Thames Water use a diagram
View attachment 111950

I haven't looked at every water company by any means. Can I ask UK members to check on their water company's website to see if they give a hardness band table.

Would be a really good feature on the website if we could collate the info for different areas

Essjay · Aug 6, 2020

Wills said:
I would imagine that the uk uses those phrases for people to consider using things like Calgon in washing machines to protect against limescale.

Companies making water softeners use the same bands.

Wills · Aug 6, 2020

essjay said:
Companies making water softeners use the same bands.

The cynic in me says that’s not a coincidence haha

Essjay · Aug 6, 2020

I knew I'd posted an image some time ago and I have managed to find it.

This is a diagram which Northumbrian Water gave up to the middle of last year, but it is in the scale mg/l calcium so I'll need to convert the numbers.

20 = 2.8 dH and 50 ppm
40 = 5.6 dH and 100 ppm
60 = 8.4 dH and 150 ppm
80 = 11.2 dH and 200 ppm
120 = 16.8 dH and 300 ppm

In other words, the same as the table in the first post

Edit to add - Essex & Suffolk Water are part of the same group as Northumbrian Water so that chart apples to them as well.

seangee · Aug 6, 2020

Southeast water now gives a number based on your address. It corresponds to my own tests

275 mg/l CaCO₃

Click to expand...

19.25 English degrees or degrees clark
27.5 French degrees
15.4 German degrees
2.75 mmol/l
15.4 Grains per US gallon
19.25 Grains per British Gallon

This means your water is classified as hard

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Hardness - words vs numbers

Essjay

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Salty&Onion

Fish Aficionado

Retired Viking

Fish Connoisseur

Byron

Supporting Member

JuiceBox52

Passionate about fish and their care

utahfish

Fish Herder

Essjay

Moderator

seangee

Fish Connoisseur

Essjay

Moderator

Wills

Retired Moderator

Wills

Retired Moderator

Essjay

Moderator

Wills

Retired Moderator

Essjay

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seangee

Fish Connoisseur

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