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Re: Seachem buffer counter ions and & green water



Tarah wrote:

> I currently use CaCl, KCl+ KSO4, epsom salts and baking soda to suplement
> my water.  I have tried using acetic acid/acetate as a buffer but that
> caused bacterial blooms or something.. not quite sure. (cloudy water
> starting ~24hrs after addition lasting ~24hrs)

Acetic acid is probably too strong an acid to act as a particulary good
buffer anyway.  The cloudiness may have been a bacterial bloom.  Acetate
is pretty good food for bacteria.

<snip>
> Maybe S04 levels are not so critical?

They aren't critical.  Among the anions common in water you need
bicarbonate as a buffer and secondary CO2 source, you need a small
amount of sulfate as a source for sulfur (an essential nutrient), you
need a very small amount of chloride (may not be essential, but it still
is used by plants) and you need some nitrate for the nitrogen.  The
balance between the various anions in fresh water is extremely variable;
plants that are at all cosmopolitan must be able to adapt to a range of
compositions.  For some sort of typical conditions you might expect
bicarb to be most common, with sulfate and chloride present in smaller
amount, and nitrate being present at levels smaller than sulfate or
chloride.
 
> I looked up the old post you mentioned and agree that some Na should be
> added.  In the Horst book he found that in a number of locals the Na levels > were higher than Mg!
 
Sodium is very commonly higher than magnesium.  I don't know that sodium
can cause problems with magnesium uptake, but you may have problems if
you get the sodium content way higher than the calcium content.  In my
tap water the sodium is 16 times the calcium level (about 100 times the
magnesium level) and some of my plants are subject to calcium
deficiencies.  Other people with similar hardness levels don't report
similar problems.

<snip>

> Maybe Alkaline buffer + baking soda would allow for a more ballenced 
> reconstitution.

That's an idea.

> also, Mn should probably be included in any DIY method as I don't believe the amounts in  Flourish (what I use) are sufficient.  Any comments?

Manganese won't stay in solution, as it forms insoluble hydroxides.  I
don't know how long that takes.  My somewhat educated guess is that if
you want some manganese in solution then it needs to be chelated and/or
added regularly, not just when you change water.
 
> Final comments; the reason I think that the green water is comming from the
> tap is because the same weekend it "appeared" my betta jugs at work also
> experienced a green water bloom.

I used to get green water blooms in one of my unfiltered tanks every
fall.  The tap water comes exclusively from deep wells and doesn't
change seasonally, so I eliminated that as a cause for the problem.  I
finally decided that it was because of the change in natural lighting. 
While the change in lighting probably triggered the problem I could
always fix the problem and usually prevent its return without relocating
the sun ;)

<snip>

> One of my lab mates proposed filter sterilizing the tap and then addng it.
> this should distingwish between algae in the tap vs. algae promoting 
> factors in the tap.

That sounds like an interesting experiment, but before you do it I hope
that you're sure you're water supply actually comes from surface water.


Roger Miller