"Cardman" wrote in message
...

Your conditions may well be too alkaline and hard for the plant to
thrive.

Maybe that is one reason why these two plants suffered a rapid death,
where only their core sections are now alive.

From what I have read Myriophyllum Tuberculatum is a little more
flexible in the water quality than what you seem to indicate, where it
just does not like the extremes.

Like my former extremely hard water.

Seems likely. I forgot to mention that the plant is also very light
demanding, which may be part of the problem.

And there they were doing so well in the pet shop with no real
maintenance sources, like a light, either. I think we know why that
is...

Because they order a bunch of new ones every week to replace the
ones that are dying? ;-)

BTW -- you should try to get those nitrate levels down. 100ppm is
definitely on the very high side where it will be toxic for at least some
fish species.

My fish can live in much higher levels perfectly fine, where they just
become unhappy in a world where algae rules. So they are very happy
with anything between 50 and 150 mg/l, when algae growth is very slow
at this level.

If your fish are happy, no prob. Some species apparently die above 50ppm.
(No first-hand experience with this for me, I'm just repeating what I've read
in various books.) But other species tolerate much higher levels, so I guess
it depends on what fish you keep.

Adding lots more plants will help in reducing nitrate
levels.

A nice idea, but what you do not mention is that plants in fact use up
very little Nitrate, which is why I would have to bed plants very
heavily for any beneficial effects.

Not sure about that. I have a fairly heavily planted tank (admittedly with
not all that large a fish load). I have to add nitrates twice weekly to keep
the level at around 10ppm. Even if I dose the tank to 20ppm, three to four
days later, it's back down to zero. The plants definitely have something to
with this. I suspect (but don't know for sure) that there may also be some
amount of anaerobic nitrate reduction happening in my canister filter
and possible in parts of the substrate.

And so there is nothing that I can really do when it comes out the tap
at 50 mg/l +-20% to begin with, where the fish pooping will only cause
it to go higher.

That is unless you know of some way to turn Nitrate into something
else that won't harm fish?

Well, you could try lots of plants, and slow filter. That will contribute
toward reducing nitrates. You also add a denitrification filter. From
what I hear, they are a bit finicky though -- the the flow rate too high
and they do nothing, and get it too low, and they put hydrogen sulfate
into the water. (H2S is toxic.) But such a filter may not be a bad choice
given that you have high nitrate levels in your tap water.

Or you could use reverse osmosis water for all your water changes
(adding the appropriate salts to bring hardness up to what you want,
of course). But that's quite tedious process compared to just running
the garden hose into the tank.

In case you are interested, then I am soon to stock a load of varies
plants that are rated in the "easy" level and suitable for my water.

My shopping list is currently...

5 x Hygrophila Polysperma
1 x Anubias Nana
3 x Crinium Thainium
5 x Microsorium Pteropus
5 x (Assorted) Cryptocorynes

The hygrophila would be your best bet as a nitrate remover.
It's quick-growing and fixes nitrates well. The anubias, java fern,
and the crypts will do their bit too, but not as effectively because
they are fairly slow-growing plants. (I don't have experience with
the Crinium.) Another one you might want to consider is Vallisneria.
Good at removing nitrates and not easily infected by algae.

At any rate, lots of plants and few fish are likely to reduce nitrates
by quite a bit. And the plants will be happy with the nitrates -- it's
food :-) Keep the plants happy by adding traces (PMDD or some
such and CO2) and you may well find your nitrate levels dropping
quite a bit.

Cheers,

Michi.
--
Michi Henning Ph: +61 4 1118-2700
ZeroC, Inc. http://www.zeroc.com