29G tank troubles,

 >>  My cardinals spend most of the time now hiding under the Java fern
because they clearly do not like the bright light. <<

 My tanks are very brightly lit, and I keep Cardinals and Discus (who
supposedly hate bright light ;-)) with no problem.  The Discus are front and
center all the time, and the Cardinals school back and forth quite happily. 
IMO, if you plant heavily enough, your fish will be perfectly comfortable.  If
the tank _is_ heavily planted and they still hide, I would look for another
reason other than the lighting.

 >>  Secondly, some of the cryptocorynes (supposedly C. walkeri and C. petchi)
which are planted in the front of the tank under the compact fluorescents are
now 10-11 inches tall whereas they were about 4" when I planted them (makes
great foreground :( ). Is this their "normal" size or some strange response to
too much light? <<

 Crypts are extremely variable plants, and grow very differently under
different conditions.  Yours are just responding to the better conditions in
your tank at this time.  Crypts will _tolerate_ low light, but many do fine,
or even better in good light.  Also, remember that most Crypts are babies when
you buy them. I have a big stand of C. Wendtii that is about 18" tall!

 >>  Thirdly I recently got brave and bought some Cabomba (prob. carolinus)
and some Rotala macranda-- any hints on growing these? <<

 Both plants need lots of light, in my experience the Cabomba needs even more
than the Rotala.  Rotala macrandra also needs a steady supply of iron. 
Although you would think this type of plant would be mainly a "leaf feeder", 
I have found that at least under the conditions in my tanks, it does much
better if I pot it up with potting soil and laterite or micronized iron.

 >>  And finally, when I started adding Dupla drops it took 10 drops a day for
a week before any iron registered on the Dupla test. Is is possible the peat
was chelating it or doing something so it wasn't measured, or could starved
plants actually use it up that quickly?. <<

 I can't answer about the peat because I have no experience with it.  But
plants _do_ store nutrients. (That's why they often grow for a surprising
length of time under even dismal conditions before finally expiring)  It is
quite common to have the plants suck nutrients up at a great rate when they
are first supplemented.  After that, you can usually back off to a steady
smaller amount.

 >> Subject: 1-year maint. <<


 I never deep clean my gravel, but my tanks are completely planted from back
to front.  I simply vacuum over the substrate surface to pick up loose
detritus and plant parts.

 My tanks are long standing, and I have had no problems with the substrate
"going bad".  So IMO, the plants are doing their job using the minerals from
any detritus that filters into the gravel.  Algae problems are a sign of
excess nutrients in the water, and signal the need for a more aggressive water
change schedule, not usually a problem with the substrate.

 Subject: plant growth cycles

 >> What controls plant growth cycles in an aquarium? Specifically I'm
wondering why without any change in water change routine, tank temp, or
lighting 4 aponogeton crispus plants lost all their leaves. <<

 Most Aponogetons naturally require rest periods which would correspond to
either cold or dry periods in their native habitat.  Even under aquarium
conditions this does not change.  It is sometimes possible to "rest" an
Aponogeton in damp sand in a cool dark place for 6-8 weeks and have it re-grow
when reintroduced to the tank.  Whether or not it re-grows depends on the care
it received during it's last growth phase.  If it does not receive sufficient
nutrients from a rich substrate and plenty of light, it will not be able to
store enough energy for another appearance.

  E-mail from: Karen Randall, 04-Aug-1995