Water Changes and Nitrates

[FishNut]

I've been reading the archives and found several people who go months
without changing their water. Their reasoning is that they have mature,
well planted tanks and their nitrate levels are under 20ppm.

1. If you can get a good equilibrium then why would you want to add tap
water to an established tank more then needed?
2. At what level do Nitrates become dangerous to fish?

I don't have a problem doing water changes. They are quite easy to do the
way I have my tank setup. However, I am trying hard to get my water
chemistry right for Angels. My Nitrates are staying below 10ppm. I've been
doing water changes every two weeks but my plants are starting to mature and
I find myself doing water changes with low nitrates. I feel that I could
probably go to monthly water changes or maybe longer. I've been monitoring
my Nitrates, GH and KH are there any other things I should be testing for or
would warrant more frequent water change?

[Dinky]

<interpersed>


"FishNut" > wrote in message
et...
> I've been reading the archives and found several people who go months
> without changing their water. Their reasoning is that they have mature,
> well planted tanks and their nitrate levels are under 20ppm.
>
> 1. If you can get a good equilibrium then why would you want to add tap
> water to an established tank more then needed?

Buildup of trace elements and minerals due to evaporation and topping off.


> 2. At what level do Nitrates become dangerous to fish?

Freshwater, 40ppm or less is considered acceptable.


>
> I don't have a problem doing water changes. They are quite easy to do the
> way I have my tank setup. However, I am trying hard to get my water
> chemistry right for Angels. My Nitrates are staying below 10ppm. I've
been
> doing water changes every two weeks but my plants are starting to mature
and
> I find myself doing water changes with low nitrates. I feel that I could
> probably go to monthly water changes or maybe longer. I've been
monitoring
> my Nitrates, GH and KH are there any other things I should be testing for
or
> would warrant more frequent water change?

You should be checking for ammonia and nitrite on occasion if you aren't
already. Both of these things are far more toxic than low levels of nitrate.
IME, a well-planted tank can go much longer between water changes than a
fish-only tank, what with the plants consuming the nitrogen, so you're right
on track with your logic. However, the presense of ammonia or nitrite would
indicate bio-filter issues rather than insufficiant water changes.


--

billy
--
Need tech help?
news://news.winextra.com

[Geezer From Freezer]

Don't forget that changing water more frequently, lowers the risk of bad
bacteria too!

[NetMax]

"FishNut" > wrote in message
et...
> I've been reading the archives and found several people who go months
> without changing their water. Their reasoning is that they have
mature,
> well planted tanks and their nitrate levels are under 20ppm.
>
> 1. If you can get a good equilibrium then why would you want to add tap
> water to an established tank more then needed?

Any equilibrium will always slowly go out of balance. NO3 is just a
convenient indicator of a water change need. There are many other things
happening in your water than you even have test kits for.

> 2. At what level do Nitrates become dangerous to fish?

NO3 is most dangerous when the levels change quickly (water shock
symptoms). There is no documented verifiable safe level for all fish.
They vary in their susceptibility to it, and the effects are not always
going to be obvious. The levels 20 to 40ppm are sometimes mentioned in
text and the web.

> I don't have a problem doing water changes. They are quite easy to do
the
> way I have my tank setup. However, I am trying hard to get my water
> chemistry right for Angels. My Nitrates are staying below 10ppm. I've
been
> doing water changes every two weeks but my plants are starting to
mature and
> I find myself doing water changes with low nitrates. I feel that I
could
> probably go to monthly water changes or maybe longer. I've been
monitoring
> my Nitrates, GH and KH are there any other things I should be testing
for or
> would warrant more frequent water change?

That you can measure, kH and pH would be your most important. Your drop
in gH would be gradual (as plants take up minerals), and NH3/4, NO2 would
be unlikely in a lightly stocked (Angelfish) planted tank. Planted tanks
reach an equilibrium with NO3, sometimes resulting in NO3 being
completely removed, so measuring NO3 is no longer a useful indicator for
when you should do water changes.

Are you injecting CO2? Are you using a bio-wheel? Have you ever
measured DOCs (conductivity test). There have been several recent
threads on DOC accumulation in alt.aquaria.

What I do is when the NO3 uptake is higher than the food chain produces
(well planted tanks), I switch to doing a 10% a week water change,
ostentatiously to replace trace minerals before they become a growth
constraint for any plants. From the viewpoint of removing DOCs, it's not
ideal, but I run low fish-loads on my planted tanks, so it works for me.

NetMax