Water Changes

[crsublette]

Randy, Total salinity in pond water is the sum of all of the mineral salts (ions) in solution. General Hardness is essentially the level of Calcium and Magnesium salts (ions) in solution. GH is a percentage of total salinity.

Only true in the very broadest sense of the term, "salinity", When no context is defined, "salinity" truly becomes a catch all term for almost all available ions present in the water. Generally, when salinity is talked about in our context or in the context of what is fresh or brackish or ocean water, then the context appears to have a focus on sodium salinity rather than "general hardness" salinity. I don't see how using the "salinity" term in this "catch all" manner is particularly helpful.

@Meyer Jordan Can you hyperlink reference me a single salinity test kit that can be used for salts involving calcium/magnesium as well as sodium and chloride?

 

[crsublette]

But as usual Meyers your reply made me think. Answer me this, if water hardness is simply the amount of salt dissolved in the water, what is the difference between General Hardness (GH) and Salinity, and why do they have two different scales for each?

They use two different scales since they are testing for different salts. Simple.

 

[Meyer Jordan]

@Mucky_Waters I have witnessed the exact same occurrence last Fall.

My little pond's water level was dropping about 2 inches every day. I was wondering... What the heck man? So I looked on the border of my pond...

Ends up, over time, dirt and debris built up in the rock on my stream's border that created a bridge for significant capillary (wicking) action. This capillary action was wicking so much water out of my stream that the outside ground beyond my stream actually became quite muddy.

I understood the capillary action, but I was floored by how much water was being wicked out of my pond.

I rebuilt my stream so that this "soil/debris capillary bridge" was tougher too occur by using different rock and not so much rock so that I can spray the soil/debris away from the border on occasion.

Since I have done this... I no longer lose up to 2 inches every day of water... I still have about a 1/8 inch water level drop every day due to a water leak in my pond that is somewhere, grrr, but at least it is water my trees that are next to my pond... So, I use a trickle of source water to solve this problem.

An evaporation rate of 1/8"/day would be a reasonable expectation.

 

[Meyer Jordan]

Only true in the very broadest sense of the term, "salinity", When no context is defined, "salinity" truly becomes a catch all term for almost all available ions present in the water. Generally, when salinity is talked about in our context or in the context of what is fresh or brackish or ocean water, then the context appears to have a focus on sodium salinity rather than "general hardness" salinity. I don't see how using the "salinity" term in this "catch all" manner is particularly helpful.

@Meyer Jordan Can you hyperlink reference me a single salinity test kit that can be used for salts involving calcium/magnesium as well as sodium and chloride?

A GH test measures calcium/magnesium ionic strength.These are only two (2) of the ions in water that comprise total salinity.
There are three (3) separate tests. One that measures only GH, the typical salinity test that measures the total strength of all Chloride (non-carbonate) ions and the Conductivity test which measures total ionic content of water. There is not one test that will measure all three (3) independently.
As to the use of the term Salinity being a 'catch-all', this is how this term is used in Chemistry and we are discussing water chemistry. Although many hobbyists may think of Sodium Chloride when the term 'salt' is mentioned. The salinity tests used by these same hobbyist measure total ionic concentration of all Chloride salts...Sodium Chloride as well as Potassium Chloride and Calcium Chloride. Sodium Chloride is what usually comes to mind when a pond keeper mentions Salt. But this is because, even though the other two salts mentioned will serve the same purpose, Sodium Chloride is more readily available and cheap in comparison.

The chart below details the 'Salt' percentages of ocean vs fresh water.

 

[crsublette]

@Meyer Jordan An excellent clarification yet does not address what wrote.

I understand we're starting to split hairs here.

Correct, when using the "catch all" context for salinity, then the term Total Salinity should be used rather than just Salinity since just the word "Salinity" on its own have a different context in the pond hobby world.

Due to the test type used, sodium salinity, or specific gravity, is the context of salinity pond hobbyist think of when using the term salinity.

Even when using a conductivity meter, mathematical coefficients are used to know if testing for chloride or sodium.

Water can have 400ppm chloride, yet still have a low specific gravity.

 

[Meyer Jordan]

Due to the test type used, sodium salinity, or specific gravity, is the context of salinity pond hobbyist think of when using the term salinity.

While in the earthen-bottom Fishery pond world this is termed a Chloride test. The word 'salinity' is rarely used when discussing this type of aquatic habitat.
Since most of my time is involved in reading research documents and articles written by those within the scientific community, it only follows that I would use the same terminology as they do.
It is also interesting to note that Ornamental fish breeders recognize that Salinity encompasses more than just Table Salt.

 

[crsublette]

@Meyer Jordan aquaculture often use 3 distinct separate salinity tests. Total Salinity. Sodium Salinity. Chloride Salinity. Then, the other elemental ions are mentioned as a salt that are as measured, not as a percentage of Total Salinity.

This due to the need to have a much higher chloride concentration while also knowing when, sodium levels get too high due to source water or fish food, to know to "desalinate" to keep a lower sodium salinity.

Ornamental fish breeders I find actually use the term hardness, rather than salinity, when talking about the other salts specifically calcium, magnesium, and the other elemental ions.

 

[Mucky_Waters]

There is something else that can happen in a liner pond that can cause a lot of water loss to happen very quickly and make someone think they have a serious leak, it has to do with the folds in the liner. When liners get laid in ponds there is always a certain amount of folds that get created, and these folds can often extend from the bottom of the pond all the way up and over the berm of the pond and back down a ways, depending on how the extra liner is left to hang over the edge, and how far. If the folds lay tight enough where it fold back on itself it can seal and create a sort of tube chamber. Under the right circumstances that tube chamber can act just like a siphon hose and siphon water from deep in the pond where the fold starts, up over the berm of the pond and down as far as the fold extends into the ground outside the pond.
These kinds of leaks are hard to trouble shoot because you can have a situation where the fold tube is there but it doesn't cause any problem until one day you over fill your pond and cause water to start flowing through the tube as the pond over fills, this gets the siphon action happening. Then, even after you stop filling your pond, the siphoning will continue sucking water out of the pond until the it reaches the bottom of the fold inside the pond, or the end of the folded liner that hangs over the berm, whichever is the highest point.

This top picture below is a cross section of the liner looking down along the side. It shows how a sealed tube can be created from a fold in the liner.

This next picture shows a side view of how the fold can act like a siphon hose

 

[crsublette]

@Meyer Jordan aquaculture often use 3 distinct separate salinity tests. Total Salinity. Sodium Salinity. Chloride Salinity. Then, the other elemental ions are mentioned as a salt that are as measured, not as a percentage of Total Salinity.

Quick correction on my self.

I think Wikipedia defines salinity quite well. (https://en.wikipedia.org/wiki/Salinity) ... "Salinity is the quantity of dissolved salt content of the water."

When a test primarily talks about Chloride, then Chlorinity, rather than salinity would be the correct term. Then, to derive a salinity % measurement from Chlorinity, a conversion is involved.

Notice that took two different water tests to derive the chloride and sodium content.

At the bottom of this post is the water test (provided by https://www.facebook.com/earthanedge/) is what I was thinking about. Sodium and Chloride was mentioned as a quantity rather than as percent of or ppt of "salinity".

 

[crsublette]

Here is a good read...

Chloride and Salinity

http://www2.vernier.com/sample_labs/WQV-15-COMP-chloride_salinity.pdf

 

[Meyer Jordan]

I think Wikipedia defines salinity quite well. (https://en.wikipedia.org/wiki/Salinity) ... "Salinity is the quantity of dissolved salt content of the water."

Which is basically the same definition that I presented.

The PDF that you posted a link to was one of my sources for the definition of Salinity also. Salinity is more than dissolved Table Salt.

 

[crsublette]

@Meyer JordanDue to the test type used, sodium salinity, or specific gravity, is the context of salinity pond hobbyist think of when using the term salinity.

Another quick correction on my part...

Not sodium nor chloride that is being tested by the typical hobbyist salinity tests... It is actually just the density of the water that is tested and this density changes with the type of dissolved salts involved...

Some salts change the density more than other salts.

 

[Mucky_Waters]

I must admit when Meyers first started claiming water hardness was basically just the salts dissolved in water I knew he wasn't wrong, but I was sure he wasn't totally right either. That got me thinking about my water softener and how I have to use salty (hard?) water to recharge the ion exchange resins in the water softener so that it can continue to soften the water. Obviously there is a significant difference between the type of "salts" being treating by those resins and the type of "salt" being used to recharge those same resins that soften my water.

Anyway, I'm no chemist but in a nutshell this is the conclusion I have come to about the difference between hard water and salinity.

Hard water is formed when water percolates through deposits of limestone and chalk which are largely made up of calcium and magnesium carbonates.

Salinity is the total of all non-carbonate salts dissolved in water.

Which I feel clearly supports Charles's statement.

They use two different scales since they are testing for different salts. Simple.

 

[crsublette]

@Mucky_Waters The hyperlink you shared also states, "hardness is determined by the concentration of multivalent cations in the water."

The "hard water" mentioned "carbonate" salts due to this is the salt that delivers, through limestome, the two most common multivalent cations (calcium and magnesium).

You can still have hard water yet still have acidic (low carbonate) water. This is due to the presence of multivalent cations in the water.

As further stated, it is "the presence of the metal cations makes the water hard."

Notice also in @Meyer Jordan table above Bicarbonate was included.

Permanent hardness is the reason why you use salty water. Skip down to the "Permanent Hardness" section in that hyperlink you posted.

 

[crsublette]

The reason Salinity also includes "bicarbonates", which is a speciation of carbonate, is due to that bicarbonates are dissolved ions in the water. As I mentioned earlier, (https://en.wikipedia.org/wiki/Salinity)"Salinity is the quantity of dissolved salt content of the water," which also includes various bicarbonate salts (that is a speciation of carbonate) as well as magnesium, potassium, nitrate, etc, etc.

"Salinity" is just a single test result of ALL dissolved salts in the water, not any particular one salt.

Theoritically, you can have a high salinity primarily composed of sulfate, calcium, potassium, bicarbonate, and magnesium and yet have negligible sodium and chloride, and the same vice versa.

Just so happens that "salt water" has a predominance of Sodium and Chloride due to the fact that Sodium and Chloride is a byproduct of decomposition and a necessary element for animal and plant Life. The Sodium-Potassium pump in fish and animals is one reason why we are able to expel the toxins from our body and Chloride is a required electrolyte that keeps the fluids managed.

Transport of ions and water across the epithelium of fish gills.
http://www.ncbi.nlm.nih.gov/pubmed/7438