Water Chemistry

[dfreas]

I finally bought GH and KH test kits last night and started testing. I
figured I should at least have some idea of how much CO2 my DIY
generator is putting into the system (not much as it turns out, but
mostly because it has slowed down over the past day or so). I was
suprised by the results. I knew my water would probably have a low
reading since it comes out of the tap around 6.8 but my tests show less
than 35ppm for KH and between 70 and 90 for GH. I didn't expect the two
to be so far apart or for KH to be so low. I was sort of expecting
something between 50 and 100 for both and for the two values to be the
same. Oh well.

Anyway it got me thinking. I usually use sodium bicarbonate to buffer
my tap water before I put it in the aquarium. Now the bicarbonate I'm
ok with - but where is all that sodium going? Is it ok to keep using
this stuff on a regular basis? I use about 1/4 of a teaspoon per five
gallon bucket every water change. Occasionally I do a water change
without adding any buffer when the water starts getting close to pH 7.

I'd like to use something else but all of the pH adjusting chemicals
they sell at the LFS don't list their ingredients and I have a long
standing rule that no chemical goes in my aquarium unless I know what
it is. There are too many products on the LFS shelf that say "helps
produce slime coat!" for me to trust anything that doesn't list exactly
what's in it. When a slogan that essentially reduces to "will irritate
the hell out of your fish!" is a selling point I worry about the
product!

-Daniel

[Elaine T]

dfreas wrote:
> I finally bought GH and KH test kits last night and started testing. I
> figured I should at least have some idea of how much CO2 my DIY
> generator is putting into the system (not much as it turns out, but
> mostly because it has slowed down over the past day or so). I was
> suprised by the results. I knew my water would probably have a low
> reading since it comes out of the tap around 6.8 but my tests show less
> than 35ppm for KH and between 70 and 90 for GH. I didn't expect the two
> to be so far apart or for KH to be so low. I was sort of expecting
> something between 50 and 100 for both and for the two values to be the
> same. Oh well.
>
> Anyway it got me thinking. I usually use sodium bicarbonate to buffer
> my tap water before I put it in the aquarium. Now the bicarbonate I'm
> ok with - but where is all that sodium going? Is it ok to keep using
> this stuff on a regular basis? I use about 1/4 of a teaspoon per five
> gallon bucket every water change. Occasionally I do a water change
> without adding any buffer when the water starts getting close to pH 7.
>
> I'd like to use something else but all of the pH adjusting chemicals
> they sell at the LFS don't list their ingredients and I have a long
> standing rule that no chemical goes in my aquarium unless I know what
> it is. There are too many products on the LFS shelf that say "helps
> produce slime coat!" for me to trust anything that doesn't list exactly
> what's in it. When a slogan that essentially reduces to "will irritate
> the hell out of your fish!" is a selling point I worry about the
> product!
>
> -Daniel
>
I believe if you're only adding sodium bicarb at water changes, the
amount of sodium in your aquarium is staying constant. You siphon out 5
gallons with 1/4 tsp worth of sodium and add it back. To keep the
sodium (or any salt or mineral) constant, you need to be doing any
evaporative top-off with distilled or RO water.

--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><

[Mean_Chlorine]

Thusly "dfreas" > Spake Unto All:

>suprised by the results. I knew my water would probably have a low
>reading since it comes out of the tap around 6.8 but my tests show less
>than 35ppm for KH and between 70 and 90 for GH. I didn't expect the two
>to be so far apart or for KH to be so low. I was sort of expecting
>something between 50 and 100 for both and for the two values to be the
>same. Oh well.

Normally you can happily ignore GH. It's of little interest to
aquarists.
Low KH, however, means you may get fluctuating pH, and that's bad.
Bicarbonate is an excellent way of adding KH quickly, a slower and
simpler method is to put a couple of limestones (or sea shells) in the
aquarium.

>Anyway it got me thinking. I usually use sodium bicarbonate to buffer
>my tap water before I put it in the aquarium. Now the bicarbonate I'm
>ok with - but where is all that sodium going?

It's in the water. It will likely slowly build up, but big water
changes will bring it back down again.

>I'd like to use something else but all of the pH adjusting chemicals
>they sell at the LFS don't list their ingredients

It's usually bicarbonate or a phosphate buffer. They don't list
content because, well, would you pay $5 for 100 grams of bicarbonate?
Some, like oak bark extract, functions mainly through organic acids
(tannins).

>what's in it. When a slogan that essentially reduces to "will irritate
>the hell out of your fish!" is a selling point I worry about the
>product!

You are completely right to be skeptical, IMO.

>-Daniel

[Squeek]

If you add sodium bicarbonate for hardness, the buffering capacity wont last
as long as adding organic lime to buffer....
"dfreas" > wrote in message
oups.com...
>I finally bought GH and KH test kits last night and started testing. I
> figured I should at least have some idea of how much CO2 my DIY
> generator is putting into the system (not much as it turns out, but
> mostly because it has slowed down over the past day or so). I was
> suprised by the results. I knew my water would probably have a low
> reading since it comes out of the tap around 6.8 but my tests show less
> than 35ppm for KH and between 70 and 90 for GH. I didn't expect the two
> to be so far apart or for KH to be so low. I was sort of expecting
> something between 50 and 100 for both and for the two values to be the
> same. Oh well.
>
> Anyway it got me thinking. I usually use sodium bicarbonate to buffer
> my tap water before I put it in the aquarium. Now the bicarbonate I'm
> ok with - but where is all that sodium going? Is it ok to keep using
> this stuff on a regular basis? I use about 1/4 of a teaspoon per five
> gallon bucket every water change. Occasionally I do a water change
> without adding any buffer when the water starts getting close to pH 7.
>
> I'd like to use something else but all of the pH adjusting chemicals
> they sell at the LFS don't list their ingredients and I have a long
> standing rule that no chemical goes in my aquarium unless I know what
> it is. There are too many products on the LFS shelf that say "helps
> produce slime coat!" for me to trust anything that doesn't list exactly
> what's in it. When a slogan that essentially reduces to "will irritate
> the hell out of your fish!" is a selling point I worry about the
> product!
>
> -Daniel
>

[Mean_Chlorine]

Thusly "Squeek" > Spake Unto All:

>If you add sodium bicarbonate for hardness, the buffering capacity wont last
>as long as adding organic lime to buffer....

What is "organic lime"? I don't know of any such substance.

[Margolis]

"Mean_Chlorine" > wrote in message
...
>
> What is "organic lime"? I don't know of any such substance.
>
>


calcium carbonate

--

Margolis
http://web.archive.org/web/20030215212142/http://www.agqx.org/faqs/AGQ2FAQ.htm
http://www.unrealtower.org/faq

[Mean_Chlorine]

Thusly "Margolis" > Spake Unto All:

>> What is "organic lime"? I don't know of any such substance.
>
>calcium carbonate

Ah. Better known as 'limestone'.

[Richard Sexton]

In article >,
Mean_Chlorine > wrote:
>Thusly "Margolis" > Spake Unto All:
>
>>> What is "organic lime"? I don't know of any such substance.

I have no problem getting organic lime. They're right next to the
organic lemons in the health food store.


--
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633CSi 250SE/C 300SD | Killies, killi.net, Crypts, aquaria.net
1970 280SE, 72 280SE | Old wris****ches http://watches.list.mbz.org

[Margolis]

>
> I have no problem getting organic lime. They're right next to the
> organic lemons in the health food store.
>
>
>


lol

;o)

--

Margolis
http://web.archive.org/web/20030215212142/http://www.agqx.org/faqs/AGQ2FAQ.htm
http://www.unrealtower.org/faq

[Mean_Chlorine]

Thusly (Richard Sexton) Spake Unto All:

>>>> What is "organic lime"? I don't know of any such substance.
>
>I have no problem getting organic lime. They're right next to the
>organic lemons in the health food store.

I *knew* I should've added "...unless we're talking fruit".... :-)

[David C. Stone]

In article >, Mean_Chlorine
> wrote:

> Thusly "Margolis" > Spake Unto All:
>
> >> What is "organic lime"? I don't know of any such substance.
> >
> >calcium carbonate
>
> Ah. Better known as 'limestone'.

And decidedly inorganic. Lime is technically calcium oxide, however,
not calcium carbonate. Slaked lime is calcium hydroxide. While this
might seem pedantic, it makes a BIG difference if you're trying to
make mortar, cement, or concrete!!

I suspect the original poster meant "organic" as in "of natural origin"
In this particular case, there shouldn't really be any difference
between lime of synthetic and natural origin, except that the later
would probably contain more magnesium oxide.

I would not recommend adding true lime (calcium oxide) to your fish
tank - it will react to form hydroxide, which will rapidly raise the
pH without contrinuting to the buffer capacity of the tank (if anything,
it would reduce it).

Here endeth today's chemistry lesson...

[Margolis]

"David C. Stone" > wrote in message
...
>
> And decidedly inorganic. Lime is technically calcium oxide, however,
> not calcium carbonate. Slaked lime is calcium hydroxide. While this
> might seem pedantic, it makes a BIG difference if you're trying to
> make mortar, cement, or concrete!!
>


technically your are right even though you are wrong ;o) actually, lime can
be calcium carbonate. Look at this website

http://hubcap.clemson.edu/~blpprt/acid4.html


here is a quote from it:

Lime. A material which, upon reaction with the soil, increases pH (decreases
soil acidity) and does not add harmful elements to the soil. Usually, lime
consists of finely ground carbonates of calcium and magnesium, although the
term also includes oxides and hydroxides of calcium.


--

Margolis
http://web.archive.org/web/20030215212142/http://www.agqx.org/faqs/AGQ2FAQ.htm
http://www.unrealtower.org/faq

[David C. Stone]

In article >, Margolis
> wrote:

> "David C. Stone" > wrote in message
> ...
> >
> > And decidedly inorganic. Lime is technically calcium oxide, however,
> > not calcium carbonate. Slaked lime is calcium hydroxide. While this
> > might seem pedantic, it makes a BIG difference if you're trying to
> > make mortar, cement, or concrete!!
> >
>
>
> technically your are right even though you are wrong ;o) actually, lime can
> be calcium carbonate. Look at this website
>
> http://hubcap.clemson.edu/~blpprt/acid4.html
>
>
> here is a quote from it:
>
> Lime. A material which, upon reaction with the soil, increases pH (decreases
> soil acidity) and does not add harmful elements to the soil. Usually, lime
> consists of finely ground carbonates of calcium and magnesium, although the
> term also includes oxides and hydroxides of calcium.

I was just going by my usual source, The Oxford Dictionary of Chemistry.
Ebbing's "General Chemistry" says the same thing, and mentions that
lime is also sometimes referred to as quicklime. Interestingly enough,
there's a photo in that book which shows a barge spraying limestone
slurry into a lake in order to raise the pH.

The site you reference is an agricultural one, and it doesn't suprise
me that "agricultural lime" is a mixture of stuff. I don't think I'd
want to put pure calcium oxide on my flower beds for the same reason
I wouldn't want to put it in a fish tank. Chemically and geologically
speaking, however, lime is calcium oxide. It's all down to context!!

[[email protected]]

$5 for 100 grams of bicarbonate? Can I be your supplier please?

[Mean_Chlorine]

Thusly " > Spake Unto
All:

>$5 for 100 grams of bicarbonate? Can I be your supplier please?

Hey find your own scam!

[Elaine T]

Squeek wrote:
> If you add sodium bicarbonate for hardness, the buffering capacity wont last
> as long as adding organic lime to buffer....

That doesn't agree with anything I learned in chemistry class.
Carbonate is carbonate, and calcium has NO effect on pH.

--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><

[Margolis]

> wrote in message
ups.com...
> $5 for 100 grams of bicarbonate? Can I be your supplier please?
>


A lot of people pay that though. A lot of people use seachem alkaline
buffer which is nothing more than repackaged baking soda ;o0

--

Margolis
http://web.archive.org/web/20030215212142/http://www.agqx.org/faqs/AGQ2FAQ.htm
http://www.unrealtower.org/faq

[Mean_Chlorine]

Thusly Elaine T > Spake Unto All:

>> If you add sodium bicarbonate for hardness, the buffering capacity wont last
>> as long as adding organic lime to buffer....
>
>That doesn't agree with anything I learned in chemistry class.
>Carbonate is carbonate, and calcium has NO effect on pH.

No, no, he's right - while it is true that the calcium doesn't really
matter, limestone dissolves slowly and is usually of much greater mass
than the bicarbonate you add to an aquarium, and so provides more
buffering under a much longer time. Also, the rate of dissolution of
limestone is directly proportional to pH, and so to the acids produced
in the aquarium.

[Mean_Chlorine]

Thusly "Margolis" > Spake Unto All:

>A lot of people pay that though. A lot of people use seachem alkaline
>buffer which is nothing more than repackaged baking soda ;o0

Pretty much all buffers which are not phosphate-based are bicarbonate,
so Seachem are not alone in repackaging bicarbonate.

[Elaine T]

Mean_Chlorine wrote:
> Thusly Elaine T > Spake Unto All:
>
>
>>>If you add sodium bicarbonate for hardness, the buffering capacity wont last
>>>as long as adding organic lime to buffer....
>>
>>That doesn't agree with anything I learned in chemistry class.
>>Carbonate is carbonate, and calcium has NO effect on pH.
>
>
> No, no, he's right - while it is true that the calcium doesn't really
> matter, limestone dissolves slowly and is usually of much greater mass
> than the bicarbonate you add to an aquarium, and so provides more
> buffering under a much longer time. Also, the rate of dissolution of
> limestone is directly proportional to pH, and so to the acids produced
> in the aquarium.
>
Ah. I was assuming molar equivalents. A hunk of coral definately
buffers more than a teaspoon of baking soda. It sure makes the water
hard, though.

--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><

[NetMax]

"Mean_Chlorine" > wrote in message
...
> Thusly "dfreas" > Spake Unto All:
>
>>suprised by the results. I knew my water would probably have a low
>>reading since it comes out of the tap around 6.8 but my tests show less
>>than 35ppm for KH and between 70 and 90 for GH. I didn't expect the two
>>to be so far apart or for KH to be so low. I was sort of expecting
>>something between 50 and 100 for both and for the two values to be the
>>same. Oh well.
>
> Normally you can happily ignore GH. It's of little interest to
> aquarists.
> Low KH, however, means you may get fluctuating pH, and that's bad.
> Bicarbonate is an excellent way of adding KH quickly, a slower and
> simpler method is to put a couple of limestones (or sea shells) in the
> aquarium.


Hopefully not out of context, but fish don't seem to care about kH, but
it's a concern to us for pH stability. In a situation where the gH is 70
to 90, you can happily ignore it, but otherwise, fish are much more
affected by gH than kH. Again, I apologise if I'm not in context, but
the post could be misconstrued by others less familiar with water
parameters.
--
www.NetMax.tk

[Mean_Chlorine]

Thusly "NetMax" > Spake Unto All:

>Hopefully not out of context, but fish don't seem to care about kH, but
>it's a concern to us for pH stability. In a situation where the gH is 70
>to 90, you can happily ignore it, but otherwise, fish are much more
>affected by gH than kH. Again, I apologise if I'm not in context, but
>the post could be misconstrued by others less familiar with water
>parameters.

I'm sorry, I don't follow - why would the fish care about the calcium
content of the water? Salinity/osmotic potential yes, certainly, but
why calcium?

[NetMax]

"Mean_Chlorine" > wrote in message
...
> Thusly "NetMax" > Spake Unto All:
>
>>Hopefully not out of context, but fish don't seem to care about kH, but
>>it's a concern to us for pH stability. In a situation where the gH is
>>70
>>to 90, you can happily ignore it, but otherwise, fish are much more
>>affected by gH than kH. Again, I apologise if I'm not in context, but
>>the post could be misconstrued by others less familiar with water
>>parameters.
>
> I'm sorry, I don't follow - why would the fish care about the calcium
> content of the water? Salinity/osmotic potential yes, certainly, but
> why calcium?


Speaking in general terms, hard water = osmotic pressure (issues of
salinity aside), and calcium is the main ingredient in hard water.
--
www.NetMax.tk

[Mean_Chlorine]

Thusly "NetMax" > Spake Unto All:

>hard water = osmotic pressure

Well... As a rule, yes, but you can have high osmotic pressure in very
soft water too. Just add table salt.

[David C. Stone]

In article >, Mean_Chlorine
> wrote:

> Thusly "NetMax" > Spake Unto All:
>
> >hard water = osmotic pressure
>
> Well... As a rule, yes, but you can have high osmotic pressure in very
> soft water too. Just add table salt.

In general, anything dissolved in the water will contribute to
osmotic pressure, even sugar! If you have hard water, however,
that is going to be one of the biggest contributing factors.
High levels of nitrate and phosphate will also raise the osmotic
pressure.

[Richard Sexton]

>> I'm sorry, I don't follow - why would the fish care about the calcium
>> content of the water? Salinity/osmotic potential yes, certainly, but
>> why calcium?
>
>
>Speaking in general terms, hard water = osmotic pressure (issues of
>salinity aside), and calcium is the main ingredient in hard water.

No, osmotic pressure is where there's a differential between two
solutions across a semipermeable membrane. Nothing to do with
hard water per se.

http://members.aol.com/profchm/osmotic.html

I wonder if the hard water problems with some fish aren't really
the ammonia-ph probelem where ammonia is more toxic at higher
pH. I notice that all the "problem hard water fish" are also
very sensitive to ammonia, and in their natural acid water they
would almost certainly never have it as a problem.

--
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[NetMax]

"Richard Sexton" > wrote in message
...
>>> I'm sorry, I don't follow - why would the fish care about the calcium
>>> content of the water? Salinity/osmotic potential yes, certainly, but
>>> why calcium?
>>
>>
>>Speaking in general terms, hard water = osmotic pressure (issues of
>>salinity aside), and calcium is the main ingredient in hard water.
>
> No, osmotic pressure is where there's a differential between two
> solutions across a semipermeable membrane. Nothing to do with
> hard water per se.

Man oh man, are you guys ever getting picky :p

The original comment from Mike was:
"Normally you can happily ignore GH. It's of little interest to
aquarists."

I'm pointing out that with water changes, or moving fish (stuff which
aquarists do) you need to be very aware of the difference in the source
water gH and the destination water gH (or in how much the gH will change
with a water change), because the difference will account for the
majority of the osmotic pressure the fish will experience, in a
freshwater aquarium, notwithstanding the use of salt, and that the major
component in gH in the calcium.

> http://members.aol.com/profchm/osmotic.html
>
> I wonder if the hard water problems with some fish aren't really
> the ammonia-ph probelem where ammonia is more toxic at higher
> pH. I notice that all the "problem hard water fish" are also
> very sensitive to ammonia, and in their natural acid water they
> would almost certainly never have it as a problem.

That sounds reasonable to me.
--
www.NetMax.tk

[Rocco Moretti]

Richard Sexton wrote:
>>>I'm sorry, I don't follow - why would the fish care about the calcium
>>>content of the water? Salinity/osmotic potential yes, certainly, but
>>>why calcium?
>>
>>
>>Speaking in general terms, hard water = osmotic pressure (issues of
>>salinity aside), and calcium is the main ingredient in hard water.
>
> No, osmotic pressure is where there's a differential between two
> solutions across a semipermeable membrane. Nothing to do with
> hard water per se.
>
> http://members.aol.com/profchm/osmotic.html

If you scroll to the bottom of the page, you see that they calculate the
osmotic pressure of a solution without regards to any specific setup. So
although osmotic pressure specifically refers to a difference between
solutions, it is also allowable to talk about the osmotic pressure of a
single solution, with the assumption the other solution is pure water.

And although *all* solutes contribute to osmotic pressure, in a normal
aquarium, the major contribution to osmotic pressure will be Ca and Mg
salts, (and NaCl in marine/brackish environments). If I understand
correctly, the amounts of uncharged and other charged salts are minimal
and can be ignored. Same sort of rational of while you can measure
"Total Dissolved Solids" with a conductivity meter (which only measures
charged ions)

Osmotic pressure usually matters because water will migrate from a low
osmotic pressure solution to a high osmotic pressure solution, until the
osmotic pressure in the two solutions are equal (... in the absence of
an externally applied pressure, blah, blah, blah). This is a well know
effect with red blood cells. If you put RBCs in low salt (hypotonic)
solution, water flows in bursts the cells. In high salt (hypertonic)
solution, water flows out and you get shriveled cells.

http://www2.nl.edu/jste/osmosis.htm
http://www.the-aps.org/education/outreach/outreach/acts-labs/halversn1.htm

And since fish gills are quite exposed to water, sudden changes in
osmotic pressure could very well cause them some discomfort.

[Mean_Chlorine]

Thusly Rocco Moretti > Spake Unto All:

>And although *all* solutes contribute to osmotic pressure, in a normal
>aquarium, the major contribution to osmotic pressure will be Ca and Mg
>salts, (and NaCl in marine/brackish environments).

Not sure that's accurate. At least in our (calcium hydroxide treated)
tapwater sodium, chloride, and sulphate are each about equal to
calcium, while magnesium is present at much lower concentration, and
bicarbonate concentration is about twice that of calcium.

> If I understand
>correctly, the amounts of uncharged and other charged salts are minimal
>and can be ignored. Same sort of rational of while you can measure
>"Total Dissolved Solids" with a conductivity meter (which only measures
>charged ions)

That assumption doesn't hold; TDS is a complete misnomer.

>And since fish gills are quite exposed to water, sudden changes in
>osmotic pressure could very well cause them some discomfort.

Going from high osmotic pressure to low osmotic pressure may kill
them. Going in the other direction doesn't seem at all as dangerous -
I've as recently as today moved fish from an aquarium with
peat-filtered distilled water and a pH of 4.5, to my pH 8.3 brackish
tank, and I acclimated them for perhaps five minutes. When I move fish
in the other direction I acclimatize them for at least an hour, and
they STILL get severely stressed.