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Plant ID and Do fish respond to GH or KH?

Subject: Plant identification

> Plant 2.
> Purchased as Aponogeton natans.
> 
> Based on pictures I have of A. natans this plant looks correct a
> description given. However what I presumed to be a flower spike 
> developed two young plants on it, and is still growing. I may be
> it is my understanding that A. natans does not reproduce in this
> this A. natans?

I had this happen once too.  I can only assume that this plant is 
a hybrid between A. natans and A. undulatus.  A. undulatus 
produces plantlets on its flower stalks similar to an Echinodorus.

Natans has been crossed with a lot of other Aponos because it is 
so vigorous.  If the hybridizer can fix the leaf characteristics 
of the the other species (avoiding natan's floating leaves) and 
still maintain the ease of culture found in natans, they end up 
with a better aquarium plant.  

Unfortunately, with this particular cross, what has been achieved 
seems no more than a curiousity.  I found that it produced almost 
entirely floating leaves on very long stems.  I completely covered 
the surface of my 70G tank, and produced _huge_ numbers of 
plantlets which added their floating leaves to the rats nest on 
the surface.  I ended up propagating them just long enough to get 
my HAP points, then passing them on to some one else.  They had 
little decorative value.

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Subject: Do fish respond to GH or KH?

> Karen writes:

> > ... almost any "community" 
> > type fish can tolerate a pH of 8 if you don't intend to breed
> > them.
> 
> OK, I intend to breed some! :)
> I'm trying to breed South American dwarf cichlids in my big plan
> Was just visiting cichlid guy extrordinaire Dave Soares, who sai
> basically that the species' ability to breed corresponds to the 
> hardness, because the harder it is, the tougher the eggs are (an
> easy for sperm to penetrate them).

Well, I'm not sure that I would count S.A. dwarf cichlids as 
typical community fish, but what he said is true.  (or at least 
there is definitely a strong correlation between water hardness 
and lack of fertility... I'm not sure that the scientists are sure 
what the exact mechanism is)

> Question: If I inject CO2 into hard water, will this effectively
> all the carbonates into carbonic acid, thus being equivalent to 
> soft water? i.e., is pH REALLY the indicator I should be keying 

No.  That's my point exactly.  Lowering the pH when you have hard 
water is not going to allow you to breed sensitive soft water fish 
either.  For that, you must produce soft water.  This can be done 
by using appropriate amounts of DI or RO water, or by using the 
old fashioned, but tried and true method of filtering the water 
through peat _before_ it is used in the tank.

The problem with the peat method in our (planted tank) application 
is that its use interferes with testing for CO2 levels.  Your pH 
will be lower than it would be with just CO2 injection because 
you've added a different type of acid. (humic acids) So the CO2 
charts are no longer valid.  So you can _think_ you have a lot 
more CO2 available for the plants than you actually have.  I don't 
believe CO2 test kits will work correctly either.  The other 
problem with peat is that it darkens the water.  This _may_ be a 
problem as far as lighting the tank is concerned.

That all said, short of RO or DI, I'd definitely consider peat the 
next best option if I wanted to breed soft water fish. It 
definitely works for the fish, and some people do very well with 
their plants in peat water too.  It's just that the carbonate 
hardness/CO2 "rules" that we've learned are no longer applicable 
without modification.

What absolutely _doesn't_ work is the use of "water softening 
resins" which replace calcium ions with sodium.  Soft water fish 
are no happier with all that salt than they were with the 
hardness.  And, to get back to where we started, the pH value 
itself is of much lower importance than the hardness.  If you get 
the water soft enough to get the fish spawning, it is unlikely 
that the pH will remain high enough to be of any trouble 
whatsoever.  The addition of pH reducing chemicals (other than 
CO2) is just not necessary, and can lead to unexpected and 
undesireable results.

Adding more chemicals to hard water to try to replicate the 
extremely pure water conditions that soft water fish come from is 
counter productive.  

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA