Echinodorus species like substrate fertilisation very very much. Adding an
iron/N:P:K root tab might help. Store bought plants in good condition tend
to store a few weeks supply of nutrients and the addition of fertilizers
will keep them bubbling for a while under ideal conditions. A stream of
tiny bubbles from just one or even a few spots on a plant could signify a
damaged part of a leaf or a disintegrating one. If the plant has decreased
in size, I really think lack of light is the limiting factor to start off
with.
An increased/growing fish load will reduce the oxygen saturation ablility of
the tank over time, ie a few tetras/cories to start off with take up less
oxygen than a big oscar or lots of angelfish or gigantic bristlenose catfish
which will consume lots of oxygen thus no visible bubbles from plants. I've
no idea at what point oxygen levels signify true pearling from plants in
tanks, but I think it's around 80%(someone correct me).
IME an unpruned tank will allow plants to cover the surface or even just
taking up space in the middle of the tank ie pennywort, or heaps of baby
echinodorus' growing from a few runners from the one plant *significantly*
reduces growth/pearling of the mother/substrate lying plants from lack of
light even with 4 tubes over a 65G.

"François Arsenault" wrote in message
. ..
Hello everyone,

During the first year of my 40-gallon planted aquarium, my plants looked
great. In particular, I had a huge, beautiful Echinodorus. My other plants
were also thriving. In fact, at times I could actually see streams of tiny
bubbles coming out of them. I assume it was oxygen, which I took as a sign
of good health.

Unfortunately, they haven't done this in a long time, and they don't look
nearly as good as before (that was maybe two years ago). If the bubbles
were
indeed a sign that the plants were thriving and producing great amounts of
oxygen, what could explain their current situation?

What puzzles me is that I'm actually taking better care of my plants for
the
last year or so. I've been adding fertilizer on a regular basis (but not
too
often or too much), and I recently started adding CO2. I've also always
made
sure I changed my fluorescent tube often enough so the light quality
wouldn't go down too much. Ok, so I only have one main light for a
40-gallon
aquarium with a large surface area, which isn't enough, but the situation
was the same when my plants were doing better.

Is there anything that could explain my plants' decreased health under
improved conditions? My old Echinodorus was 4 times the size of those I
have
now, and it didn't tend to turn yellow or brown or lose leaves like the
current ones do. The situation is similar for other species. Could it be
that I now have too many plants? I'm pretty sure I have more now than 2
years ago. Are they competing with each other or something?

I realize that it could be any number of things, but any advice would be
greatly appreciated. Thank you.

Francois