re: Growth has stopped

---------- Forwarded message ----------
Date: Tue, 5 Nov 1996 16:14:54 -0500
To: Aquatic-Plants at actwin_com
From: krombhol at tiger_teclink.net (Paul Krombholz)
Subject: Re: Growth has stopped

>I planted E. tennellus in my 55, and true to form it took off and made a
>very attractive carpet in the foreground.  About a month ago, growth
>stopped and now many of the leaves are transparent.  Nothing has changed
>that I am aware of - weekly water changes 10-20%, lights on a timer
>12H/day, 2 40W bulbs 1 full spectrum and 1 warm spectrum (they are about
>5 mo. old), temp 78F, pH 7.2, inconsistent addition of FerroVit, regular
>gravel no addition to substrate.  Any suggestions to stop the trend and
>get back to growth and runners?
..................<rest snipped>.......................

When you say that many of the leaves of the E. tenellus are transparent, I
assume that you mean the older leaves, and that they are dying back, and
you are seeing just the dead veins with the tissue in between gone.
Someone else has suggested potassium deficiency, and that is a good
possibility.  Postassium deficiency causes older leaves to develop small
dead spots that spread and become more numerous until the entire leaf is

Another nutrient to seriously consider is magnesium.  Magnesium deficiency
also causes older leaves to die back.  Typically, they lose chlorophyll and
become yellow before dying.  Often the edges and end of the leaf turn
yellow and start to die while the midrib is still green.  Magnesium
deficiency has not been considered very much, but it could be more
prevalent than most aquatic plant people think.  If you come from a
dolomite limestone region, the water will have both calcium and magnesium
hardness, but if you come from a soft water region, the municipal water
system may add some lime to the water to give you moderately hard water,
but that water will have very little magnesium.  Fishfood is not a good
supplier of magnesium, either.  MgSO4 is easy to get.  I got what probably
will be a lifetime supply---five pounds---at a local garden supply store
for five or six dollars.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In chilly Mississippi, where I am hoping they can get the heat working in
the science building before the next cold front comes.