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Re: Crypt growing w. Val and Ceratophyllum in sunlit tank

Roger Miller wrote:

>I understand the reasoning here that crypts shouldn't be tried in a tank
>where hyrophila fails.  What puzzles me is that I have a sunlit tank w/o
>added CO2 where the pH exceeds 9 and hygrophilla has failed but where C.
>wendtii (? <shrug>) and C.  balansae thrive along with Elodea,
>Ceratophyllum and Vallisneria.  The wendtii in fact have been in nearly
>continuous, submersed bloom for the last 6 weeks.

That is very interesting! You say that Hygrophila failed, but that C.
wendtii thrives.  I have been making the assumption that crypts would be
like the Hygrophila.  Crypts may have something going for them when it
comes to fighting for CO2 in a low CO2 environment that I don't know about.
Actually, I did have one experience that agrees with yours.  I had a tank
with some crypts and Limnophilia aquatica get taken over by green water.  I
got too busy to do anything about it for 6 months, and the tank had bright
light (15 gallon with 3 20 watt fluorescents) no fish and no CO2 or any
organic matter added for 6 months.  The Limnophilia died away completely,
and I was sure that the crypts would be gone, too, but when I lifted up the
tray out of the murky green water, to my surprise, they looked pretty good
and had even grown a little since they had disappeared from sight 6 months
ago.  Green water algae (at least the kind I get) can utilize bicarbonate
and raise the pH just as high as Elodea or any of the other aquatic plants
adapted to low CO2 situations.

It may be that the tolerance that Crypts have for low light situations is
basically that they can get along with very little net photosynthesis per
day.  In dim light the net photosynthesis (=the amount of sugar made in
photosynthesis minus the amount used up in respiration) is low, and yet the
crypts do well, although they grow slowly.  Perhaps in bright light-low-CO2
situations the crypts are getting the same result---low, but positive net
photosynthesis. Income is still a little more than expenses.

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.

>Is it possible that these species could store CO2 at night while the
>others respire, then use it in the day (what I think I've  read described as
>acid crassularian metabolism) or that they may be capable of getting CO2
>through their roots like Isoetes ferns?
>Roger Miller
>Too curious to keep my mouth shut.
That could be.  Curiouser and curiouser!  Can't keep my mouth shut, either.
I can see that there is a need to try a lot of plants that look like they
need high CO2 in well-lit low-CO2 tanks with Elodea and Val to see how they


Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In Jackson, Mississippi with sunny, pleasant spring weather.