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Re: A rigidifolia failing/Kent Marine pH Stable

On Fri, 9 Jun 2000, Christina Samuels wrote:

> First question: When I first set up my tank my Apon rigidifolia grew
> robustly, sending up flower stalks every week, it seemed like. Now, however,
> most of the leaves seem to be turning transparent, and the stalks are
> getting mushy. The leaves eventually die. Is this a fault of my water? Or do
> these plants need more than a Flourite substrate?

The initial growth from Aponogetons is from the nutrient and energy stores
in their tuber.  If the nutrient supplied to the plant aren't sufficient
to maintain growth over a longer period then the plant will grow
(sometimes burgeon) rather briefly, then collapse.  That may be all that's
happened to your plant.  The low pH may also have some effect.

Low pH, incidentally, generally suppresses bacterial activity and
favors growth of fungi.

> Second question: is a product like pH Stable better than baking soda to add
> buffering capacity to my tap water?

It would be easier to advise you on what to do if we knew your existing
general hardness and buffer capacity.

In most senses, baking soda is the best thing you can add to tank water to
add alkalinity; it's readily available, inexpensive, fairly pure and quite
effective.  I don't know how any commercial hobby alternative can improve
on it, and at least some of the commercial products (I can't say for sure
that this is the case with the Kent Marine product) contain phosphate that
you generally don't want in your tank.

The one drawback to using baking soda is that you are adding sodium to the
tank along with the buffer capacity.  Plants don't use sodium, so that
part is a rather useless addition to the water.  Also, if the general
hardness in your water is low then the added sodium could potentially
throw the balance of electrolytes off to the point that you may see
deficiencies in calcium (and possibly magnesium or potassium) that you
wouldn't otherwise see.

An alternative is to use shells, limestone chips, dolomite chips or marble
chips from garden supply stores.  All of these dissolve gradually to
provide buffer capacity plus calcium and (in some cases) magnesium.
Calcium and magnesium will increase your general hardness and both are
essential plant nutrients.  Shells can be put directly into the tank.
Chips are more easily placed in a mesh bag and either placed in the filter
or directly in the tank.  The shells or chips can be removed when the pH
and buffer capacity rise to where you want them to be.

Roger Miller