Re: Alkalinity

To: Aquatic-Plants at actwin_com
Subject: Re: Alkalinity
From: Elizabeth Worobel <eworobe at cc_UManitoba.CA>
Date: Sat, 11 Jan 1997 09:57:35 -0600 (CST)
Cc: Aquatic-Plants at actwin_com
In-Reply-To: <199701110839.DAA17998 at looney_actwin.com>
> Hi everyone,
> 
> The other day I picked up Tetra's book "Aquariology, Master Volume". In it,
> it states:
> 
> "Sodium Bicarbonate is a pH adjuster rather than a buffer. If added in
> excess to an aquarium, the pH can be elevated to unacceptably high levels.
> A 10% solution of baking soda can safely be used to raise the pH of an
> aquarium.
> ...
> Also, since Sodium Bicarbonate by itself is not a buffer, the desired pH
> may not hold for very long."
> 
> So, who's right? Or am I confusing KH (Carbonate Hardness) and Alkalinity
> (Acid Binding Capacity)? Am I totally confused yet????

George, of course, is correct. As usual the so called aquarium 'experts' 
havent got a clue. Sodium bicarbonate adds inorganic carbon to the water. 
(HCO3). The inorganic carbon equilibrium CO2/HCO3/CO3 is the MAIN 
buffering system in fresh water, so if you add more bicarbonate then you 
increase the buffering capacity of the system. End of story!
The best part of adding sodium bicarbonate is that hardness is completely 
unaffected.
On this list we have agreed that KH and alkalinity are synonymous. In 
actual fact KH is that portion of the alkalinity whose charge is balanced 
by divalent cations such as Ca and Mg ... in other words KH is a measure 
of hardness and has nothing to do with total alkalinity (since charge can 
be balanced by any number of cations).

> I DON'T want to use phoshate buffers and any product which doesn't list
> it's contents makes me nervous. 

Excellent strategy.
 
> I have a bottle of Seachem Reef Builder, which I use for my marine tank.
> Would it work (in small quantities)? The label states that it will raise
> and maintain alkalinity, restore calcium, magnesium, strontium and trace
> elements. It claims to not directly alter the pH of the water and the
> contents are listed as Sodium, Magnesium, Calcium, Strontium and Potassium
> salts of Carbonate, Bicarbonate, Chloride, Sulphate and Borate.
> 
> What do the chemists think? Can this product be used in freshwater tanks
> (in appropriately smaller quantities) to increase the Alkalinity of the
> water while leaving the GH alone (or at least at a low level)? If not, what
> can be used (other than Dupla's KH builder tablets) to accomplish this
> task?

This is not an appropriate product. It contains divalent cations which 
will increase your hardness (GH). It also contains carbonate and 
bicarbonate so it WILL increase your pH. George's advice (which I 
snipped) is still the best ... to increase pH stability but not hardness, 
add sodium bicarbonate to your tank water.

dave.