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Why hard water fish species NEED hard water (and visa versa for soft)

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Stephen:
Why hard water fish species NEED hard water (and visa versa for soft water fish species)

This is a fairly short post but I have added two links at the bottom which will give more detail and make interesting reading.

When sites like fishbase.org or seriouslyfish.com mention water hardness, they are referring to dGH (degrees German hardness).
General hardness (GH) refers to the dissolved concentration of magnesium and calcium ions. GH which is the general, total or permanent hardness which is a measure of the overall concentration of calcium, magnesium and other ions., not to be confused with KH which is the Carbonate hardness (the K is from the German Karbonathärte) which is a measure of the water hardness caused by the presence of carbonate and bicarbonate anions.
When fish are said to prefer "soft" or "hard" water, it is GH (not KH or pH) that is being referred to. Some people also confuse pH with hardness; pH and hardness (GH) are two different things and are not associated. pH determines if your water is acidic (below pH7.0) or basic (alkaline) (above pH7.0). pH7.0 is pH neutral.

So these websites when referring to hardness then it is:- GH
Soft = 0-2.8 dGH or 0-50ppm
Moderately Soft = 2.8-5.6 dGH or 50-100ppm
Slightly Hard = 5.6-8.4 dGH or 100-150ppm
Moderately Hard = 8.4-11.2 dGH or 150-200ppm
Hard = 11.2-16.8 dGH or 200-250ppm
Very Hard = 16.8+ dGH or 250+ppm
(some sites specify slightly different/higher figures).
dGH = degrees German hardness

So despite my KH = 4, my dGH = 5 (tank); my tank water is therefore moderately soft.
My tap water is GH=4.6 or 4.6dGH (API test kit states 5) so is moderately soft.

Fish (freshwater and saltwater) use osmosis and diffusion to regulate their bodies this is known as Osmoregulation (the ability to regulate osmosis).
Water goes in through the mouth, out the gills, out the skin and excreted; this is then replaced by minerals taken into the skin, or through the gills and vice versa.
Without this system a fish would either suffer from lack of the correct balance of minerals (hard water fish in soft water), or too much of one or more minerals (softwater fish in hard water), resulting in some form of deficiency.
This is often what leads to things like kidney failure in fish and eventually death.
Fish osmoregulation is needed by fish because fish live in an environment where these are readily available to them, which is why the correct balance of your water parameters is so important to your particular fish.



Examples of hard water fish species:- Molly, Guppy, Endlers, Swordtails, Platy, African Rift Cichlids (Lake Malawi, Lake Tanganyika), Many Rainbowfish and many more species.

Myth: because your local fish stockist (LFS) stocks and sells both soft water and hard water fish species it does not mean that you can also stock those fish.
You need to determine what your water hardness is which can easily be done by checking your water company's website or buying a water hardness liquid test kit such as the API GH/KH test kit.
I have listed links to many (not all) water company websites at the bottom of this page.

I am amazed that a vast majority of fish stockist (LFS) whether national or highly respected independents do not know about KH or GH.
All they are generally more concerned about is pH and temperature. ... and sales.

Water company websites:

Affinity Water
Anglian Water
Bournemouth Water
Bristol Water
Cambridge Water
Dee Valley Water
Essex & Suffolk Water
Hartlepool Water
Northumbrian Water
Portsmouth Water
Scottish Water
SeS Water
Severn Trent
South-East Water
Southern Water
South Staffs Water
South West Water
Thames Water
United Utilities
Welsh Water
Wessex Water
Yorkshire Water

Immolo:
Thanks for this especially the link to the Portsmouth water section as when I previously just googled it I could onky find the actual break down of the water quailty who would have thought they had it in an easy to find place on the main homepage roflmao

blackghost:
I have water too.    *bye3*

Used to be North West Water, the biggest in the land (area served), till it merged with Norweb (North West leccy board) to become United Utilities.

https://www.unitedutilities.com/services/your-water-supply/

@Stephen, you're welcome to add this one to your list and delete this post.

Stephen:

--- Quote from: blackghost on May 25, 2018, 02:32:03 am ---I have water too.    *bye3*

Used to be North West Water, the biggest in the land (area served), till it merged with Norweb (North West leccy board) to become United Utilities.

https://www.unitedutilities.com/services/your-water-supply/

@Stephen, you're welcome to add this one to your list and delete this post.

--- End quote ---
United Utilities is already on my list ;)

blackghost:
I need to go to specsavers.   roflmao

Didn't see this either.  *2116*

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