Re: conductivity

[David Sanchez <barbax2@yahoo.com>]

Great discussion on water quality were having here. I
have had several people contact me regarding this
topic as well as Johns e-mail here so I think I will
answer here for the benefit of all. I am happy to see
that we are beginning to see the importance of
conductivity. However I feel there is still some
confusion on what I am saying. Hopefully we can
clarify a few things here. Conductivity is basically a
measurement of water hardness. However once we have a
baseline for example if we produce water with a
conductivity of say 10 us/cm. Then we know we have
very soft water. However once we have this baseline we
continue to test our water. We learn very quickly that
it rises over time. Is the water hardness going up? 
Of course not. We are now measuring the Dissolved
Organic Compounds or DOC?s. I have found that a
conductivity meter is a superior way to measure water
quality. As urine, feces, ammonium, nitrates,
decomposed matter in general accumulate the
conductivity rises as well. So yes water hardness or
conductivity is important to get eggs to hatch but
that?s easy. I think all of us can get o DH water of
low counductity water. The trick is to monitor water
quality via our conductivity meter and then we know
where we stand. As I have explained this is the #1
killer of fish eggs and fry after we have the proper
parameters. Think about many of you use 0 DH low
conductivity water but still no egg; eat the eggs, or
no parental care. There is more to it then just
correct water parameters. It has been said that pH is
not as important. That is correct but the key is not
water hardness but rather KH. South American fish eggs
and all soft water acidic species are very sensitive
to a high KH. Indeed this is what determines pH. So as
long as you have a 0 KH your pH will be low and your
fish eggs should hatch. You will not have a low
conductivity if your KH is high. KH is a measure of
carbonate hardness. It relates to the ability of the
system to maintain equilibrium of Carbon. A low KH
means lots of Carbonic acid in the system and thus a
tendency to have a low pH and the opposite is true of
a high KH.

In summary of all this we can have water that has a 0
DH but high in DOC?s by say fertilizers added to the
water from runoff or from some additives were adding
to the aquarium, by what we feed etc etc many things.
The key is clean water. Again our fish hail from very
clean pristine pure water and they are very sensitive
to pollution. And how do we measure the pollution? 
DOC?s and we measure that with a conductivity meter.
It can be logically assumed that when we have a high
level of DOC?s we will also have a high bacteria level
in the tank from the decomposition. We don?t always
see this like when we find a dead fish. There is a
microscopic world we never see but we should take into
account. A big help in this are plants that suck the
nutrients out of an aquarium and water changes!

Now to John?s last question concerning fry. I believe
in water changes. I recommend daily 100% water changes
on fry. Many of my Apisto fry are sexually mature in
3-4 months. Why water changes low DOC?s Folks DOC?s
will kill fish eggs and fry and will make parents eat
their eggs. Pollution kills fry. On the other hand if
you have a tank full of polluted water and do a 100%
water change to clean water the shock may kill the
fish! This is a frequent occurrence with wholesalers
and Petshops. You take the fish home they look healthy
and wham you put them in clean water with low DOC?s
then shock they just got their system shocked. This is
due to the drastic change in ionic balance. Well I can
ramble on for days here. I hope I helped everyone.

Dave


--- John McCrone <j.mccrone@btinternet.com> wrote:
> [David Sanchez]
> John the overidding factor is the water quality. And
> that goes in 2 parts. One is having the proprer and
> correct parameters the secound in maintaining very
> good water quality which translates to low DOC's as
> can be measured by our counductivty.
> 
> [John McCrone]
> I've  never focused on conductivity simply because a
> meter seemed
> expensive - over £100 in the UK from memory. DOC is
> dissolved organic
> content? And is this what is directly measured by a
> conductivity measure?
> 
> I use London water which I presume is high in DOCs
> already - it certainly
> tastes that way and I even carbon filter it for my
> own consumption! I use an
> RO unit in the hope that most of the crud is
> removed, then add about 10
> percent tap water (which is GH of 15-20 and pH of
> 7.5-8). My fish never
> survived that long until I switched to RO.
> 
> Do you think eggs are more vunerable than fry to
> water quality? Now that I
> have fry, I am debating when to do the next water
> change. Normally I would
> change about a third every other week on this 20
> gallon tank, well planted,
> with only two little rams. But in the past, I've had
> a lot of fry (of other
> apisto breeds) die after about a week. This didn't
> matter as I could only
> house enough survivors to replace their parents. But
> if you want a high
> survival rate, what is the balance between water
> changes and disruption?
> 
> Cheers
>
------------------------------------------------------------
> from John McCrone
> 
> 
> 
> 
> 
> 
>
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