Vreejack
May 21st 07, 08:20 PM
On May 21, 7:50 am, "Alan Holmes" > wrote:
> "Les Hemmings" > wrote in message
>
> ...
>
> > Alan Holmes wrote:
> >> "Rich" > wrote in message
> ...
> >>> Hi,
>
> >>> I change 20% of the water in my 180L Tropical Freshwater Aquarium
> >>> every week.
>
> >> Why, it is not neccesary!
>
> > I've bred Kribensis, kept a "general tank" and also kept some very fussy
> > Discus. A regular water change of 10% to 20% depending on pollutant levels
> > is normal practice. The idea of the perfectly balanced tank needing only
> > top ups to replace water lost from evaporation is a myth.
>
> As I've said before, I kept tropical fish for many years, breeding them for
> sale to the local tropical fish shop, and I never, ever changed the water.
>
> If your tank had a proper number of plants in it the water will stay
> healthy.
>
Plants will remove a lot of metabolic wastes and heavy metals, but
I've found that a natural substrate with a lot of clay and humus works
even better. Sand and gravel do not provide enough of a reaction
surface to bind soluble nutrients, but clay has a surface area four
orders of magnitude higher than sand and is naturally negatively
charged and so in an aerobic environment (the top millimeters of soil
or anywhere near a plant root) it binds the Fe+++ and Cu++, reducing
metal toxicity and still making nutrients available for plant roots.
These soils will also pull HPO4- and HPO4-- as the phosphates are
bound to the iron and iron oxides. Humic substances in such soils
also bind readily to Fe++, Cu++ and Zn++, making them much more
available for plants than metal oxide precipitates. You don't get
much of this with gravel, and if you run a UGF you raise your soil
redox too high, making plant roots almost useless.
On the other hand you face a different problem when you do not change
the water. Lots of plants release toxins (allochemicals) into the
environment which kill other plant species which might compete for
resources. I recently added some plants to my tank and one of them is
killing my parrot feather. Who'd have thought something could kill
parrot feather? Yet every day another stalk dissolves into a black
thread. Some of my Phyllanthus fluitans are also dissolving (but
others are very strong). Most of my plants are growing so well that
you can see by the change in leaf size where in their growth history I
planted them, but some plants refuse to play nicely together.
> "Les Hemmings" > wrote in message
>
> ...
>
> > Alan Holmes wrote:
> >> "Rich" > wrote in message
> ...
> >>> Hi,
>
> >>> I change 20% of the water in my 180L Tropical Freshwater Aquarium
> >>> every week.
>
> >> Why, it is not neccesary!
>
> > I've bred Kribensis, kept a "general tank" and also kept some very fussy
> > Discus. A regular water change of 10% to 20% depending on pollutant levels
> > is normal practice. The idea of the perfectly balanced tank needing only
> > top ups to replace water lost from evaporation is a myth.
>
> As I've said before, I kept tropical fish for many years, breeding them for
> sale to the local tropical fish shop, and I never, ever changed the water.
>
> If your tank had a proper number of plants in it the water will stay
> healthy.
>
Plants will remove a lot of metabolic wastes and heavy metals, but
I've found that a natural substrate with a lot of clay and humus works
even better. Sand and gravel do not provide enough of a reaction
surface to bind soluble nutrients, but clay has a surface area four
orders of magnitude higher than sand and is naturally negatively
charged and so in an aerobic environment (the top millimeters of soil
or anywhere near a plant root) it binds the Fe+++ and Cu++, reducing
metal toxicity and still making nutrients available for plant roots.
These soils will also pull HPO4- and HPO4-- as the phosphates are
bound to the iron and iron oxides. Humic substances in such soils
also bind readily to Fe++, Cu++ and Zn++, making them much more
available for plants than metal oxide precipitates. You don't get
much of this with gravel, and if you run a UGF you raise your soil
redox too high, making plant roots almost useless.
On the other hand you face a different problem when you do not change
the water. Lots of plants release toxins (allochemicals) into the
environment which kill other plant species which might compete for
resources. I recently added some plants to my tank and one of them is
killing my parrot feather. Who'd have thought something could kill
parrot feather? Yet every day another stalk dissolves into a black
thread. Some of my Phyllanthus fluitans are also dissolving (but
others are very strong). Most of my plants are growing so well that
you can see by the change in leaf size where in their growth history I
planted them, but some plants refuse to play nicely together.