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Re: trimming/ pruning/ maintaining crypts

J. Miller wrote:
>  I was always under the impression that crypts were low light plants.
>But both Paul and Roger have stated that they grow like weeds (my
>paraphrase ;-) under what I would call high light.  I keep my crypts
>under the shadows of swords, and lilies, thinking that that's the best
>way to grow them.
>  I do have 80W of florescent light over my 35 gal plant tank, but I
>have placed all of the crypts out of direct light.  Will they grow
>faster, larger, more if I move them into direct light?
>  BTW, substrate is mostly just plane gravel, but it has, up until a
>few months ago, been a *fish* tank for several years.  I also added
>some left over Flourish and a few Jobes Spike for Ferns.  Should be a
>good rich substrate, right?

I would think that your crypts would do better in the direct light,
provided there are enough nutrients.  I have seen tanks where plants that
are more brightly lit look worse than the same species growing in dimmer
parts of the tank.  I am pretty sure that when nutrients are low, the
poorly-lit plants look a lot better because they have enough nutrients, and
the better-lit plants are deficient because, with more light, they need
higher levels of nutrients because their demands are higher since they are
trying to grow faster.

Crypts are tolerant of a wide range of light levels, and it is easier to
keep them in relatively low light because nutrients aren't drawn down so
rapidly, and there is less chance of algae take-overs.  They can be grown
in high light, and they do very well, provided that you keep the nutrients
up and the algae under control.  I have sometimes had very good growth with
Crypts in tanks that got sun.  I have also had good growth sometimes in 15
gallon tanks with four 17 or 18 watt T-8 bulbs, although I have also had
algae take-overs that my snails and Daphnia never seemed to be able to

I have just started working with the compact fluorescents, and the problem
of algae take-overs seems much greater.  With these powerful lights (80
watts on a 15 gallon tank) I have had a tank go very low in nutrients, even
when I thought I was adding enough.  Since the plants looked extremely
nitrogen deficient, I added a larger dose, and green water took over in one
day.  In just one day, the tank went from clear to a dense green that I
couldn't see more than three inches into. Also, all the mulm at the bottom
develped bubbles, and about half of it rose to the surface and turned into
a cyanobacteria mat.   I currently am entertaining a hypothesis that my
algae-control crew, snails and Daphnia, do not do well on algae that is
highly nitrogen deficient, and the algae can accumulate, although it isn't
especially visible.  Under these conditions, the plants look severely
deficient, too.  When I add a big dose of nutrients, the algae takes over
in only a day or two in the intense light, and the nutrients and CO2 get
sucked down to zero rapidly.  the snails and Daphnia don't have a chance.
With the very intense light, the green water actually killed the Daphnia
population, which under dimmer light would thrive on and eliminate the
green water.

I want to see what happens if I start a tank with lower light, get the
nutrients high and the snails and Daphnia on top of things, and then switch
to the compact fluorescents and keep the nutrients high by testing daily
and adding hefty doses.  Since I suspect that the algae gets all set for a
take-over when the nutrients are low, making the algae possibly inedible
or, at least, non-nutritious, for snails and Daphnia, I am hoping that by
keeping the nutrients high, the algae will remain nutritious and edible,
and the snails and Daphnia will be able to keep it under control.  We will

I have a low light tank (about 1 watt per gallon from a T-12 lightstick
with a piece of aluminum foil serving as a poor reflector) with some crypts
that look quite nice, although they have grown very slowly.  the tank also
has a big bunch of Microsorum and floating Ceratopteris, further shading
the Crypts.  This is a guppy tank, with no Daphnia, obviously.  I havn't
taken a nitrate reading for a long time, but I would be surprised if the
nitrates were not at least 10 ppm nitrate-N.  I would like to see what
happens to this nice stable system when I pop the 80 watts of compact
fluorescent on it.  My guess is, that the nitrates would drop rapidly, and
so would the CO2, provided that I did not start supplementing what the
guppies normally add.  The pH would go up to over 8, the nitrates down to
zero, and green water would take over.

Paul Krombholz, in cool, dry, central Mississippi.