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Re: Lowering pH when adding hard water nutrients to soft water
>From: "David A. Youngker" <nestor10 at mindspring_com>
>This point _is_ rather indisputable, and is one of the "given"s of the
>It's the final effect on the tank that worries people where it's not
>it's too easily avoided to spend much more time than to acknowledge the
>possibility because this is the most "normal" and sane position to adopt in
HAR HAR! I would venture a guess that this is the first time in the history
of the list, and likely of humanity, that someone's sanity has been
questioned over their water-change philosophy!!! Seriously, thanks for the
critique Dave. With challenge comes change; change, progress.
> I'd say its importance lies in overemphasizing the results.
The results are not overemphasized (?) - they are the simple product of the
treatment. Such a simple experiment does serve to emphasize an
oft-overlooked effect. The impetus of the experiment was my father's poor
goldfish tank, which rarely gets a good change. He challenged me to put
numbers on the effect, and there I went.
> many aquarists (I, fortunately, know of none personally) who let 20% of
> their tank evaporate and then simply top it off.
Yikes. Recall the last bout of replies after my last post on this topic.
The Walstad (no change for 6 months) fans emerged en force; one chap hadn't
done a water change in 2.5 and another for 3 years! [c'mon Krombholz and
Gomberg, you still there?] They are out there, they are numerous, and if
their techniques work for them, well bless their little hearts. I am green
with envy. I am not trying to make everyone do things my way (most folks
don't need to), just to put numbers on long-held assumptions.
I keep a lot of Amazon stuff (plants, fish, amphibs) at home and at work. I
try to keep the water soft and the lights blazing. I can easily lose 2%
tank volume to evaporation in 1 day. The practice of topping off with RO
water clearly contributes to the maintenance of stable conditions longterm.
Note that this purist practice is not warranted in every or even most
plant/animal applications, especially where evaporation is low and large,
regular water changes are common practice.
Furthermore, most plants/animals can clearly withstand large changes in
conductivity. Consider the tadpole that begins life in a rain-filled pond
and crawls out as a froglet after the pool has been reduced by evaporation
to a puddle. Or the plants that live in seasonally flooded forest streams.
They can easily persist.
However, the long-term effects of using whole water to top off in aquatic
systems that receive small water changes can be substantial. It is just one
more potential source of stress for plants and animals already stressed by
life in captivity, and it is easy enough to avoid. So change large / change
often, or topoff pure. 'Nuf said.
> From: "Roger S. Miller" <rgrmill at rt66_com>
> You don't have to let 20% of you water evaporate to see an effect. Several
> of my tanks have been in continuous operation for years. After a few years
> of 15% weekly changes I've measured specific conductance in my tanks
> approaching twice the value in my tap water. Specific conductance is a
> semi-quantitative measure of salt content.
> Salt concentrations will tend to rise over time to the point where the
> amount of salts you remove during one water change is equal to the amount
> you add to the tank with water changes, or between changes with top up,
> fertilizing, feeding, medication and so on. In my house, the older the
> tank, the higher the salt content.
Thanks, Roger, for corroborating my suspicions and preliminary results.