[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Effects of roots, sinking vermiculite
As a newcomer to APD, I have been enjoying the various discussions.
I have just been getting back into the aquarium hobby after several
years out of it, and there have been a few changes!
Steve Pushak wrote
>I don't believe I said that the transpiration stream of submerged
>aquatics is responsible for aeration of the substrate. I have said at
>other times that the aerenchyma of stems and roots DOES provide oxygen
>in the substrate and that in some circumstances, plant roots could grow so
>densely over time that the reduction of iron would be greatly diminished.
A number of years ago, I was doing some post-grad research involving
the rooted aquatic Lagarosiphon major (a significant aquatic weed in
this country). At one time I grew some plants of this in transparent
plastic containers (disposable tumblers I think) and the zone of
richly red-brown oxidised iron surrounding each root was very
striking, especially against the blackish reduced sediments in which
the plants were rooted.
This oxidised zone was about 2 to three times as wide as the root,
as I remember, so a dense root mass would have just the effect that
On another theme, I read of the use of vermiculite as a medium for
aquatic plants, and tried the recommended method of waterlogging it -
repeated squeezing and kneading. This seemed to be getting me
nowhere, so I used lake sediment (there is a lake at the bottom of my
garden) instead. However, I subsequently tried placing a bowl full
of very wet vermiculite in the microwave oven. After a few minutes
heating it came to the boil, the vermiculite expanded somewhat then
started falling to the bottom of the water column. Some still
floated, and a second microwave treatment fixed that.
Readers may care to try this approach. Assuming that NZ vermiculite is
the same as that elsewhere, it may save some trouble. A week later, the
vermiculite is still submerged, and I was able to remove the fines by
washing it as if it was gravel, by using a gentle flow of water
upwards through it.
Rotorua, New Zealand