Re: [Killietalk] I need some help with water chemistry and additives questions.

[Barry Cooper <bjc3 at centurytel_net>]

Jason,

I don't have time this morning to answer this message in full but I will 
make the following comment:

Re alkalinity. When referring to aquarium water this term is synonymous 
with buffering capacity. That is, it is a measure of how much acid or 
base the water can "absorb" without significantly changing the pH. It is 
essentially a measure of the amount of bicarbonate in the water. Sodium 
bicarbonate is not the only source of bicarbonate ions, but is the 
easiest to add. Sodium bicarbonate will increase the pH of the water 
because it is the salt of a strong base and a weak acid. If you were to 
use calcium bicarbonate, for example, it would not affect the pH as 
much. Water that naturally has significant buffering capacity and some 
degree of hardness contains both calcium and bicarbonate ions so at 
least some of the buffering capacity is in the form of dissolved calcium 
bicarbonate. The latter is more soluble than calcium carbonate but still 
not particularly soluble. So, it is possible to have water that is near 
neutral pH with significant buffering capacity and hardness. Buffering 
capacity is important in aquariums as pH crashes tend to occur in poorly 
buffered water. You can mimic the natural situation by adding a little 
sodium bicarbonate to water that has some hardness (i.e. some calcium 
ions). Do this in a large volume so the solutions are dilute, or the 
calcium bicarbonate will precipitate.

The reason books say not to use acid and alkaline buffers in planted 
tanks is that they are typically phosphate buffers. Addition of a lot of 
phosphate will encourage growth of algae.

If, after adding Equilibrium, your water is too alkaline, you could very 
carefully add muriatic acid (hydrochloric acid). You will need to add it 
drop by drop until the pH stabilizes where you want it. Also be careful 
not to get it on your skin or near your eyes. It is concentrated. If it 
changes the pH too much when used concentrated, dilute some first.

Whether you need to do anything depends on the pH after you add the 
Equilibrium and the bicarbonate. If the pH is no more than 8 and if you 
are doing partial water changes, I wouldn't mess with it. I think you 
would find that the pH "self adjusts" as you add the water change to the 
old aquarium water. Just monitor it to find out whether that is the case.

Barry

Barry J. Cooper
Sweet Home, OR 97386



Jason wrote:
> [I tried posting this 2+ days ago, but it never appeared on the mailing
> list, I am posting it again here.]
>
> A recent question I posted on a planted tank forum has re-opened
> questions I have about water chemistry, specifically when mixing new
> water for water changes. I thought I had started to get a handle on
> this, but now I'm not so certain any longer. In general, my questions
> form around re-mineralization, carbonates/bicarbonates, pH, hardness
> and alkalinity (just to name a few!).
>
> All of this centers around how I have been mixing water change water
> for all of my tanks (planted, killies and some livebearer) over the
> last year or two. I have been, without any obvious problems, mixing up
> a 20 gallon bucket of fairly hard water, then diluting that as
> necessary depending upon which tank(s) I am changing the water for. The
> mixture I had settled on (about a year ago) is: 20 gallons of city tap
> water, 16g Seachem Equilibrium, 12g Seachem Alkaline Buffer, 6g Seachem
> Acid Buffer (that is 2:1 ratio for pH7 as per Seachem's instructions).
> This resulted in water of approximately 450-500ppm TDS, pH 6.5-7.0, and
> alkalinity of ~4-4.5dKH (I forgot to take note of GH reading, but I
> think it is between 4-6dH).
>
> I had settled on this mixture as a result of some experiments while
> teaching myself about water chemistry for my planted and killie tanks.
> My concern at first was, for my planted tanks, that my city's water was
> too soft (~40ppm TDS, 0-1dH, 0-1dKH), but thankfully neutral (7pH). So
> I started adding some Equilibrium which worked nicely by adding Ca and
> Mg for the plants.
>
> Then I was concerned about the acid buffering capacity and the fact
> that alkalinity was so low, and that the fish waste would precipitate a
> rise in NH3/NH4, drop the pH and generally create a toxic environment.
> Then I started to mix in Alkalinity Buffer. This, of course, drove up
> the pH. That made me concerned for the soft-water fish (ie. killies),
> which seem to want/prefer neutral to acidic pH's. I could not figure
> out how does one get some buffering, yet keep a neutral pH. Then I
> found Acid Buffer, and after some wrangling and experimentation,
> started to use it.
>
> I had these concerns both from readings, and observations (even if
> ultimately incorrect). I then just got very used to mixing my source
> water in that fashion, and had not questioned it. Until now!
>
> I've never had any problems with the water (per se) with regards to
> fish health. However, as mentioned above, a recent question on a
> planted tank forum got me a reply saying it's really not a good idea to
> use pH altering products in planted tanks. (I am assuming, until I get
> a further reply, that they're referring specifically to Acid Buffer, as
> I believe Alkaline Buffer is "effectively" baking soda/powder for
> bicarbonates).
>
> Now, I would *really* prefer to only have one way to mix the source
> water for all water changes, and dilute as necessary for the intended
> destination tank.
>
> With regard essential for fish health and breeding, rather than plants
> per se, I have the following questions:
>
> (1) Do I even need to worry about alkaline buffering? If so, that will
> always raise the pH, correct? And if so, how the heck does one get
> alkalinity and a neutral to acid pH? (That doesn't seem possible to
> me.)
>
> (2) When talk is of "remineralization" (say for RO/DI water), is it
> referring only to GH, and therefore Ca and Mg addition to the water?
>
> (3) Does NaCl come into play with killies at all, beyond some of my
> readings recommending it to help prevent/cure ich?
>
> (4) Can "ideal" water parameters be broken down by genus of (killie)
> fish? That is, would, say, Aphyosemion and Fundulopanchax use very soft
> (<100ppm) water, and Nothobranchius use medium-to-hard water (200+ppm)?
> Does one genus like or need NaCl? (I think this one is a big can of
> worms, no pun intended.)
>
> (5) Could I possibly make this posting more complicated?
>
> I currently keep: Fp. gardneri Misaje, Fp. cinnamomeus, Ep. roloffi,
> Plataplochilus cabindae, A. congicum Z82/17 (fry growing out from
> eggs), A. bivittatum Funge (fry growing out from eggs), Procatopus
> similis Moliwe, Simpsonichthys reticulatus Xingu (growing out from
> eggs), and Terranatos dolichopterus (eggs not yet hatched). There are
> some others not yet hatched from eggs yet, notably a couple of Notho
> species. For livebearers I have panda guppies, and Limia tridens.
>
> Again, I apologize for the long message here, but I felt the background
> might help avoid a long back-and-forth questioning and assist in
> getting to the point(s)! And point me in the right direction. I don't
> mind doing more reading, research and experimentation. I've just lost
> the forest for the trees, so to speak. :-)
>
> { Jason Stanford - rusticitas at yahoo_com - Bethlehem, PA, USA }
>
>
>        
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