The reasons for water changes

[Flash Wilson]

Hi,

When I was new to fishkeeping, I was told that water changes
were to reduce the level of nitrates. Now, my tanks have lower
levels of nitrates than my tap water, so this isn't a great plan.

I'm starting to hear more about dissolved organic compounds which
can be harmful? Can someone explain this to me in laymans' terms?
I did A level chemistry, but appear to have forgotten it.

Also, has anyone tried Tetra EasyBalance, which claims to reduce
the need for water changes if you add it to the tank every week?
How does this work in light of the reasons for water changes?

I guess you can't go without water changes forever, or you get
the situation where the pH will crash, and then a water change
would alter the water parameters so far that the fish would be
shocked. Other than this I am curious.

I am probably guilty of doing water changes far less often than
I should (except my unfiltered Bettas) but I haven't had any
illness in my large tank, and my cardinals in my smaller tank
prefer older water, from what I read. Although I do change it
a bit to stop the pH crashing (again). And they have all been
happy and healthy for months (somehow. Despite my screwing up
their pH.)

Anyway in short it strikes me that what I was told about making
water changes to reduce nitrates isn't true, or isn't the whole
truth. I'd like the full answer :)

--
Flash Wilson
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Drop me an email! Available across London or working from home.

[Iain Miller]

"Flash Wilson" > wrote in message
...
> Hi,
>
> When I was new to fishkeeping, I was told that water changes
> were to reduce the level of nitrates. Now, my tanks have lower
> levels of nitrates than my tap water, so this isn't a great plan.
>
> I'm starting to hear more about dissolved organic compounds which
> can be harmful? Can someone explain this to me in laymans' terms?
> I did A level chemistry, but appear to have forgotten it.
>
> Also, has anyone tried Tetra EasyBalance, which claims to reduce
> the need for water changes if you add it to the tank every week?
> How does this work in light of the reasons for water changes?
>
> I guess you can't go without water changes forever, or you get
> the situation where the pH will crash, and then a water change
> would alter the water parameters so far that the fish would be
> shocked. Other than this I am curious.
>
> I am probably guilty of doing water changes far less often than
> I should (except my unfiltered Bettas) but I haven't had any
> illness in my large tank, and my cardinals in my smaller tank
> prefer older water, from what I read. Although I do change it
> a bit to stop the pH crashing (again). And they have all been
> happy and healthy for months (somehow. Despite my screwing up
> their pH.)
>
> Anyway in short it strikes me that what I was told about making
> water changes to reduce nitrates isn't true, or isn't the whole
> truth. I'd like the full answer :)

I too would like to understand more about what these "DOC"s are......I've
got a similar situation.

I am changing less water & generally meddling less than I used to & to be
honest Ithink my tanks are better for it - they look & feel more stable &
established. If your Ph/Kh is dropping too much you can always throw in some
Sodium Bicarb to re-buffer the water - I've been using quite a lot of it
lately because I am running in a Nitrate filter & it seems that while it
eats the nitrates it also eats the Kh out the water!

rgds

I.

[Donald Kerns]

Flash Wilson wrote:

> On Sat, 2 Aug 2003 12:46:10 +0100, Iain Miller > wrote:
>>I too would like to understand more about what these "DOC"s
>>are......I've got a similar situation.
>
> Aye, when I reseach DOCs I am told that in a marine tank, a protein
> skimmer removes them. In a tropical tank, chemical filtration (e.g.
> carbon layer) removes them. I use carbon in my filter. So what are
> these DOCs and do I need to do water changes to reduce them?

Frank on alt.aquaria is probably a good choice to ask about DOCs. His
take is to prevent them in the first place...

Anyhow, there are a whole lot of different things that build up over
time in a tank. DOCs, Total dissolved solids, salt levels, etc.

Lot's of things that we don't have simple measuring kits for. Just
because we don't observe them doesn't mean that they're not there...

If you have non-planted tank, the nitrates will build up. The rule of
thumb is that if you change the water enough so that the NO3 stay under
control, you're probably doing OK on the other "stuff" you can't
measure.

Frank can tell you about bacteria that will break the DOCs down if given
proper conditions, but we're getting pretty esoteric at that point
(IMO).

-D
--
"When you've lost your ability to laugh, you've lost your ability to
think straight." -To Inherit the Wind

[Racf]

"Flash Wilson" > wrote in message
...
> On Sat, 2 Aug 2003 12:46:10 +0100, Iain Miller > wrote:
> >I too would like to understand more about what these "DOC"s
are......I've
> >got a similar situation.
>
> Aye, when I reseach DOCs I am told that in a marine tank, a protein
> skimmer removes them. In a tropical tank, chemical filtration (e.g.
> carbon layer) removes them. I use carbon in my filter. So what are
> these DOCs and do I need to do water changes to reduce them?
>
> >I am changing less water & generally meddling less than I used to &
to be
> >honest Ithink my tanks are better for it - they look & feel more
stable &
>
> Mine too - my 4ft tank only gets a 10% change now and then e.g. if
> there have been issues such as the filter off for a while. It seems
> stable, and the fish have never been ill in that tank either.
>
> >established. If your Ph/Kh is dropping too much you can always throw
in some
> >Sodium Bicarb to re-buffer the water - I've been using quite a lot of
it
> >lately because I am running in a Nitrate filter & it seems that while
it
> >eats the nitrates it also eats the Kh out the water!
>
> Aye, I've been using sodium bicarb to raise the KH a little, and all
> seems stable now in the 2ft tank, but I monitor it carefully. I had
> to use more bicarb than I'd been told in order to get any improvement
> at all, but all seems good now.
>
> So, let's hope someone can answer the question on water changes.
>
> --
> Flash Wilson - http://www.gorge.org
>
> Comments in my journal or guestbook are welcome!

I believe you are correct on many of the points you made. The contents
of DOCs is far beyond my abilities to specify. Simply its organic
waste......dissolved fish pooh.....dissolved fish food......the part of
fish tinkle that's not ammonia.....proteins, fats, carbs, various wastes
produced by cellular respiration......all sorts of organic
junk........complex molecules containing carbon.......beats me
really..... Activated carbon removes it..Organics stick to carbon
very well.....In the olden days that's really the only way they were
removed because water changes were taboo......

Since you are using carbon (which is not the fad these days) your water
changes can surely be reduced. Tracking the DOCs is important.... I
simply use a TDS/conductivity meter and monitor the tank water value.
My base point is my change water....and I monitor the tank water for the
delta between my change water and the tank water. When it gets to a
certain point....I do a waterchange to lower it back down......Works for
me...... Carbon will reduce the value as well.....

Any bio additive that can actually reduce DOCs is going to be strains of
bacteria that will feed on components of it and produce other waste
products....perhaps not completely DOCs. I hear these called good
bacteria sometimes in marketing literature...

Perhaps a scientific type can elaborate on your root question....I would
like to know, too.....

[~Vicki ~]

I don't know anything about all the tec stuff. But I do know that once
I started doing weekly water changes some years back I stopped having
problems of any kind in my tanks. I don't ever have to use chemicals
besides a de-chlor and have never had any fish get sick.

Now I realize that everyone has different types of tanks and I also know
that different fish types need different water parameters. This just
seems to work for me.

Vicki