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Re: Lowering pH when adding hard water nutrients to soft water

> Date: Thu, 31 Aug 2000 17:47:52 -0400
> From: Susi Barber

> I live in Vancouver, which has very soft water with no hardwater
> nutrients.  I have very small tanks, a 3 gal and 6 gal Eclipse...
> I am trying to get the plants growing healthily as an end in itself,
> but also to get rid of thread algae - and I don't have room for a FFF!
> I researched and found that the problems were more than likely
> due to the lack of magnesium, potassium, and calcium.  After
> fiddling round with dolomite...adding calcium...and Epsom salts,
> I found it too hard to try to work out how much of each to add in
> such small tanks; also, the pH kept going sky high...
> the pH obviously, is rising all the time with all of these buffering
> additives - adding enough Equilibrium to get to 4 degrees GH,
> plus Bicarb soda to get to KH of 4 (there is 0 calcium in the tap
> water), means a pH of 8+.  I was using vinegar to reduce it
> (from 8.0 + to my goal of 7.0)...
> Other solutions I have read about to reduce pH are to use peat,
> not really practical for me unless I want brown water, I don't have
> the set-up to pre-filter it with carbon to remove the tannins as
> suggested in a post on the Krib; or to use CO2 - not something
> I really want to do, I prefer the low-tech approach...

I envision a "low-tech" approach as an attempt to stabilize the aquarium
environment to conditions that would "naturally" support themselves with
minimal intervention. The greater the degree of "intervention" the higher
the likelihood that you'll need a "gadget" to support the attempt - up to
the point where your fishroom begins to take on the appearance of an
intensive care ward.

You can certainly avoid the "necessity" of the majority of the gear, but in
order to do so you have to have a solid understanding of what goes into
creating the range of "natural" conditions. The pH - KH relationship forms
part of the "core" of that understanding, and your experimentation with it
shows that you're willing to come to terms with the concept. There are a
couple of things that would make your learning curve a little smoother.

The ratio of carbonates you're providing to an ambient level of carbon
dioxide won't support a neutral pH. If you enter the CO2-KH-pH Table at a KH
of 4 you'll find that the only way to support a pH of 7.0 is with a CO2
content of around 15 ppm. This level of CO2 will not sustain itself within
the small confines of the aquarium - you'd either have to supplement or have
very stagnant, organic rich water undergoing massive amounts of decay. The
former is out due to your personal preference, while the latter isn't
exactly everyone's goal in a home aquarium.

Not that a neutral pH of 7.0 is all that natural to begin with. Freshwater
usually comes in two "flavors" - soft and acidic or hard and basic.
"Neutrality" is a human-established concept useful as a base reference for
understanding specific types of changes to a solution. It's nearly
impossible (I say nearly because, who knows, someone may actually discover
it in Nature one day) to achieve the "pure water" neutral point because it's
nearly impossible to have a container of "pure" water - water too easily
approaches the concept of a "universal solvent".

You _can_ achieve neutrality by carefully controlling the amounts of
compounds dissolved in the water, using the actions of one to offset the
other. In our case, we look to carbon dioxide and the bicarbonates, both
naturally-occurring and readily available. Returning to the Chart and
entering on the CO2 side of things, you'll find that at ambient levels of
CO2 a KH of 1.5 is required to maintain a 7.0 pH. That's almost 1/3 the
level you're trying to "force", and since the ratios are too far out of
balance you find yourself in a constant battle to keep it there.

The only mention of fish you made was that you didn't have room for the J.
floridae. Is this because the tanks' bioloads are already "maxed", or are
these plant- only tanks? Basically, I guess I'm asking just why a pH of 7.0
is deemed so important? Being off a little one way or the other isn't a
major concern with fish, and most plants would prefer soft, slightly acidic
conditions. Is the natural pH of your water system too far out of line?

You can increase calcium and magnesium without affecting pH, especially if
all you need are trace amounts for "nutrition". There may already be enough
of these compounds available in the water - everyone from the Vancouver-
Seattle area always seems to report some very fine water conditions. Is it
possible to alleviate all of these headaches by simply increasing the
frequency of your water changes?...


David A. Youngker
nestor10 at mindspring_com