water conditioners and iron

> From: "A. Inniss" <andrewi at u_washington.edu>
> Date: Mon, 23 Dec 1996 02:35:38 -0800 (PST)
> Subject: Water conditioners & Iron
> 	It just recently occured to me that my water conditioner is most
> likely affecting the iron levels in my tank, since it claims to "detoxify
> heavy metals." 
> 	Now, it is my understanding that it does so by chelating them.
> This point leads me to a few questions:
> 	1). Is the iron I add not making it to my plants? If the water
> conditioner is merely chelating the heavy metals(including, presumably, iron),
> then is the iron made forever unavailable,or is the iron now in effect double
> chelated?  (I use Flourish, whose iron is already chelated).  If the iron
> is simply "double chelated," then I presume it would eventually be
> available?

I don't quite know what you mean by double chelated, although it sounds 
like it belongs in a SeaChem ad.  ;)

I would assume that Leo is using EDTA to chelate the iron in flourish.  
It is probably stronger than the thiosulfate in the water conditioner you 
are using.  
> 	2). If it turns out that this particular water conditioner _is_
> going to make iron unavailable, what water conditioners (if any), do the
> rest of you use?  

I doubt that thiosulfate is a long-term problem with iron.  Indeed, I am 
skeptical as to how effective it is in tying up any heavy metal for the 
long-term in the aquarium.  Metal salts precipitated by thiosulfate 
should be liberated when the thiosulfate is oxidized.  
> 	3). As a related question, what does happen to the excess
> chemicals from water conditioners if they are not all used up doing their
> job of eliminating chlorine etc.?  Can some of them continue to build up
> in the aquarium, since they have nothing to bind with, or do they
> dissipate, react with other chemicals in the aquarium, or do something
> else?  

Thiosulfate reacts with dissolved oxygen in the water.  Terminal reaction 
products are, I believe, sulfur and sulfate ions.
> 	4). The listed ingredients of the water conditioner are: 

> K CO3,

Probably KHCO3, potassium bicarbonate

> C12H22CaO14, 

calcium gluconate

>Na HCO3, 

sodium bicarbonate

>Na S2O3, 

sodium thiosulfate


got me.  Could be either something with a carboxylate and an alcohol or a 
carboxylate and an aldehyde.  If the latter, then it is probably used to 
react with ammonia and be a dechloraminator in conjunction with the 

> C10H14N2O6, 

EDTA, a chelating agent.


A surfactant.  I see no reason for its inclusion.


I'm guessing that this is in polymeric form.  Probably starts as a 
benzene derivitized with an aldehyde and amino group, which should 
spontaneously couple to form a high polymer, fairly hydrophillic, but my 
guess is that the tween is present to disperse it.

> I don't recognize some of these, and with the many isomers possible, don't
> even know where to begin tracking them down.  (George, think you could
> pester your wife with this ;-)? ). Others I suspect are listed
> inaccurately:e.g. that should be K2CO3, not K CO3, shouldn't it? 

I guess my question is, why are you using this water conditioner?  What 
do you think it is doing for you that a few drops of sodium thiosulfate 
would not do?