Re: [Killietalk] tap water buffers

["David Lains" <david at zfin_org>]

Hi Scott

Alum is often used as a flocculent to pull particles together making
mechanical or settling filtration more effective.

I the Northwest where we often use acidic river water they like to use
Calcium oxide (CaO) to increase the pH of the water and alum to pull out mud
or organics.

The EPA regulates the amount of heavy metals in tap water.  This is measured
at the customers tap so they have to provide water to your house that does
not leach metal out of your pipes.  The utility can't change your pipes but
they can alter the pH of the water making it less aggressive.  Low pH water
leaches metals out of pipes and or removes mineral scale that forms a
protective coating on the pipes.

Here's a link on lead and copper rules. 
http://www.epa.gov/safewater/lcrmr/index.html

Last I heard the Alzheimer aluminum connection has been resoundly
discredited.

I'm not sure about the phosphoric acid but it sounds reasonable to dissolve
scale in the pipes but could expose the pipes to heavy metal contamination.

Carbonates are the most common water buffering system but other systems do
occur.  I think Barry has had a great time with silicates in his ground
water.  Barry?

Best Fishes
David 

-----Original Message-----
From: killietalk-bounces at aka_org [mailto:killietalk-bounces at aka_org] On
Behalf Of Scott Davis
Sent: Tuesday, October 10, 2006 7:32 PM
To: killifish discussion list
Subject: Re: [Killietalk] tap water buffers

Both the threads on RO water and Air exchangers vs. dehumidifiers have been
very useful and offer considerable food for thought. It is sobering what
some dehumidifiers, tap water and water softeners can leave in our
aquariums' waters. Thank you for asking questions some of us don't even know
to ask and thank you for the insights offered by the answers.

Brian raised the question was to what might have been added by the local
municipal water department to buffer the water so that it was running at a
pH of over 7. I think Wright, probably 1,000s of posts ago, first brought
this concern to our attention.

As a decidedly non-chemistry oriented person, there are times when I hear
things and do wonder if I'm just getting ushered down the garden path. It
seems that one discussion on-line (which naturally I can't find) indicated
that some sort of aluminum (alum?) was sometimes used to buffer the water.
In this age where people are wondering about a connection (in the popular
mind anyway) between Alzheimer's disease and aluminum, I wonder at that.

Another conversation with a gentleman at a fish shop in New Baltimore, MI
again ambled into the topic of water chemistry and municipal water. He
contended that his community, "as odd as it sounds" according to him, added
phosphoric acid, to the water. He suggested that "they" added that acid so
that it would combine with minerals in the water and the resulting scale
would coat old lead pipes, protecting them from dissolving in the tap water.
He then fretted about the declining diameter of everyone's pipes.

Are the natural buffers in water usually some sort of carbonate? Is there a
reluctance among municipal water people to add more of those compounds
because of the additional calcium and magnesium which would be introduced to
the system?

Are buffers using aluminum being used to buffer tap water or is that
miss-information? Are there cases of phosphoric acid being used to coat
municipal pipes?

What else is being used to buffer tap water? What impact may these things
have on our killies . or us?

Thanks and all the best!
Scott
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