Prakash wrote:
Hi,
I've got a 42 UK gallon tank, sand substrate, DIY CO2 and a number of
plants. ph is 7.6, GH and KH hover around 12 degrees. I'm new to this, and
have had the tank for about 12 weeks. Initially I had a lot of plants (dont
know all their names yet), and they all seem to be growing well. However I
have had increasing trouble with the fine leaved plants such as elodea,
cabomba etc. All of them seen to rot at the base and then just float up and
swirl around in the circulation. The leaves etc seem fine, its just the base
that rots.

My experience in the states with elodea is that most specimens sold in pet
stores (especially the chain stores) are not well off to begin with. I usually
would buy some to nurse some new side sprouts out of (the "branching" new light
green growth that will occur at a leaf whorl) and typically the old growth
would start disintegrating away. The new growth though was quite healthy and
would keep growing even under less than ideal conditions. So, with the elodea
at least (never messed with camboda), look for the new growths and pinch them
off from the original plant when they are a few inches long or when the
original plant starts disintegrating, whichever comes first. If you aren't
getting new growths, then that's another can of worms.

You should also try prolonging the life of the old growth by pinching off any
disintegrating portions as you notice it. I also let the majority of my elodea
free-float as I seem to remember that trying to "root" it in the gravel would
often lead to disintegration problems, but it's been a good 10 years since I
last tried to root it in the gravel. Once it gets going well, you can tell when
it's happy because this plant likes to pearl like there's no tomorrow when
conditions suit it. I used to have a little 2 gal killi fish tank in a sunlight
window (that was the only light source) with elodea and the streams of bubbles
would be constant during the day, so it doesn't take much to make it happy.