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crypts and bicarbonate

> From: krombhol at felix_teclink.net (Paul Krombholz)
> Date: Mon, 24 Mar 1997 20:31:57 -0500
> Subject: Re: Crypt growing w. Val and Ceratophyllum in sunlit tank
> This makes me wonder why the Hygrophila craps out in the same situation.
> When I have it with Ceratophyllum or Vallisneria in a well-lit tank, its
> leaves slant downwards and it quits growing entirely and gradually
> deteriorates.  You don't suppose that Crypts can utilize bicarbonate???  I
> do know that Crypts really respond to high levels of CO2, especially in
> bright light by growing much more rapidly.

That's exactly what happened to my Hygrophila.  First they stopped 
growing and the leaves pointed down, then the lower leaves fell off 
leaving a skinny little stalk with a tuft at the top.  Ugly.

Since Crypts reportedly grow mostly emersed in nature (I do wonder about
C. balansae, though) I wouldn't expect them to have the adaptations
necessary to use bicarb.  But this is the second year of their thriving in
the same brightly lit, CO2-depleted tank, so I speculate that they might
be more well-adapted to submersed growth then I've been lead to believe. 
I wonder if, given sufficiently bright light and a period of time, they
would be able to switch their metabolism from using CO2 to using

If its possible, then I think *really* bright light might be required.  I
can easily imagine a case where the light is bright enough that other
plants or algae will strip CO2 out of the water but there isn't enough
light available for the Crypts to overcome the barriers to the change.  In
that case, the crypts would not thrive. 

In my case, the plants get about 2,000 watt-hours/square meter during the
winter from direct sunlight (based on local solar energy data, adjusted
downward for the time they actually receive direct light) plus
supplemental lighting at 3 watts/gallon.  By contrast 4 flourescent tubes
(2,900 lumens each) over a 55 gallon tank would provide less than 575
light watt-hours/square meter in a 12-hour period - that is *if* I
remembered the lumen to light watt conversion correctly.  I used 680
lumens per light watt. 

I suppose it would be possible to test their bicarb utilization by
isolating them in a sunlit tank w/o CO2 sources and measuring the pH and
alkalinity over a period of time.  The trick would be to keep algae from
screwing with the results.  Or maybe not.  That seems too simple. 

> Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
> In Jackson, Mississippi with sunny, pleasant spring weather.   
Roger Miller
In Albuquerque, New Mexico with snow on the flowering fruit trees.