Re: Aquatic Plants Digest V2 #220
Question: What is a reasonable amount of time to wait after you try
something (i.e.,try a new fertilizer, try a new lighting scheme, etc...)
before you can say that the new change either helped, hurt or did not
affect the plants?
I had some experiences a little while ago that illustrate that sometimes
you can see the results almost immediately, and other times, you may have
to wait for several weeks. Interestingly, they were both responses to
The first was with an Echinodorus uruguayensis (narrow, green leaved form)
that I was growing in a 75 gallon tank with four 40 watt T-12 tubes on 15
hours a day, and CO2 additions. I also just described the setup when
talking about horemanii flowers yesterday. The plant was growing rapidly,
when I noticed white spotting on the leaves. These spots were the tissue
between the veins, and in some of the leaves, it soon died. I suspected
calcium deficiency, and I added a pretty good dose of Hoagland's solution
macrountrients(which contains calcium), specifically 7 liters. Also, I
added about a half teaspoon of lime. The plant, however, continued to
produce leaves with the white spotting for another three weeks. , and so I
dropped the idea of a deficiency and began speculating that I had some
problem with soil toxicity. The soil I was using was what I call "soil
soup" where I take ordinary topsoil, mix water into it until it is about
the consistancy of runny pudding or thick soup. Then I filter it through
window screening to filter out all the roots and other undecomposed stuff.
I pour this in trays and cover with about an inch of gravel.
Anyway, I had myself talked into thinking that this soil soup might become
toxic because it rather suddenly (compared to what goes on in the formation
of aquatic soils in nature) goes from aerobic to anaerobic, and I was
thinking that perhaps concentrations of reduced iron or possibly other
elements got high enough to be toxic.
Finally, the plant started sending up normal, nonspotted leaves, and then
floating leaves, as I described yesterday. I developed an arguement that
the recovery of the plant could be due to the increasing density of roots
in the soil, aerating it and perhaps reducing the toxicity that way, or by
just absorbing the excess iron or whatever.
Something happened in another tank of mine that has got me thinking again
in terms of calcium deficiency. I cleaned out a 15 gallon by changing
about 95 % of the water and removing the trays of plants that were in
there. I left the population of ramshorn snails undisturbed, and they
didn't seem to be bothered by the water change. I put in a large plant of
Ceratophyllum, and, two days later, I could see new growth that looked
quite pale. Iron deficiency, I thought, not surprising, since I didn't
have any source of iron for the plant at all. However, after another two
days, the growing tips died and fell off. This rules out iron deficiency
and points to calcium deficiency. In general, calcium deficiency does its
damage at the growing points of roots and shoots. Severe deficiency causes
the growing points to die, and less severe causes distortions of forming
leaves, smaller leaves, and often an uneven distribution or loss of
chlorophyll in the newly formed tissues. I have seen calcium defiency in
Vallisneria where the new leaves are highly distorted, looking like they
have been folded back and forth like the bellows of an accordion. They are
much lighter green and have white streaks. With somewhat more severe
deficiency the leaves are very short and white, and they disintigrate soon
after they are formed.
I was surprised that my Ceratophyllum was showing what looked like calcium
deficiency so soon, just four days after I changed the water. I thought,
since my water came out of the tap with a pH of 8.5 and had some buffering
capacity, that it had some calcium. Since I have no way of testing
chemically for calcium, I added about 1/4 teaspoon of lime to the tank
along with some CO2 to help the lime get dissolved without the pH going up
a lot. In only two days, the Ceratophyllum had made a complete recovery
with new growth coming out all over the plant. The new growth was much
healthier, although still a little reddish because of the low iron
availability. I am 100% convinced that the plant had calcium deficiency
and that the lime cured it.
I had no idea that my tap water was that low in calcium. It must have
virtually none at all for the plant to get seriously deficient in only four
days. That makes me start thinking about the white spotting on my Sword
plant's leaves. If those spots were calcium deficiency there must be an
explanation why the plant kept producing leaves with the symptoms so long
after I had added calcium. In contrast to Ceratophyllum, where the growing
point is exposed and visible, in Echinodorus it is hidden deep down in the
stems of the older leaves. I have no idea how many minniature leaves are
folded around the growing point, each a little longer than the next. It
may be that the leaf that emerges today was formed three weeks ago and
calcium deficiency signs could have been imprinted on it at that time.
At any event, I am not sure at all that soil toxicity caused the white
spotting. It could have been calcium deficiency, after all.
What started all this was the question, how long do you have to wait? It
could be just a a day or two, or it could be as long as a month.
Subject: Is CO2 heavier than air?
CO2 is heavier than air, but when it is mixed with air it doesn't separate
out again. The kinetic energy of the CO2 molecules is very great and it
gets them mixed evenly by the process of diffusion in any gas mixture. If
you had a container starting with a layer of CO2 on the bottom covered with
ordinary atmospheric air, the CO2 would become evenly mixed with the rest
of the air in a matter of an hour or less. I believe that Dixie Lee Ray
made the arguement that CFC's could never get up to the ozone layer to
participate in its destruction because they were too heavy, but she was
wrong, worng, worng.
>Subject: Hello and Anubias
The book, Aquarienpflanzen, by Christel Kasselmann, has a lot about
Anubias, including pictures of just about every Anubias I ever heard of and
some I never heard of. You can order it at the following web site:
It will cost about 54 dollars, but it is worth it for the pictures and the
revised taxonomy alone. It is in German.
Paul Krombholz Tougaloo College, Tougaloo, MS 39174
In pleasant Mississippi.(High temps less than 90 degrees F.)