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Re: Optimum current in planted tank + H corymbosa
- To: aquatic-plants at actwin_com, bhunter at rainbow_descon.com, booth at hpmtlgb1_lvld.hp.com, eworobe at cc_umanitoba.ca, krandall at world_std.com, krombhol at felix_teclink.net, liem at direct_ca, nfrank at mindspring_com, olga at arts_ubc.ca, oya at med_unc.edu, rodgers at direct_ca
- Subject: Re: Optimum current in planted tank + H corymbosa
- From: spushak at CCGATE_HAC.COM
- Date: Thu, 07 Aug 97 13:51:25 PST8
Frank I. Reiter" <FIR at istar_ca> asks in the 8/7/97 Aquatic Plant
Digest what is an optimum current for plants?
If your plant leaves are moving slightly this is an indication of
turbulent flow which is what you want. Turbulent flow greatly
increases the mixing of the fluid (water) at the boundary layer of the
leaf which improves the transfer of water containing CO2 to the leaf
surface where it can be absorbed. If you have CO2 injection, high flow
rates will also increase the surface interaction of the water and
result in a lower CO2 concentration at dynamic equilibrium. Again,
this gas interchange is greatly increased when there are turbulent
flow regimes at the water surface which are characterized by small
disturbances in the water surface e.g. ripples, eddies, any visible
disturbance. If you have bottled compressed CO2 and you are running
trickle filters, box filters or the like, the additional CO2 you need
to inject may not be worth worrying about. If you are using yeast CO2,
you probably want to take every precaution to minimize surface
disturbances in your water.
As an aside, I have a Hygrophila corymbosa (or stricta) which sits in
the current from my powerhead which I use to inject CO2. I use a half
inch tube about 6-8" long to improve the CO2 dissolution rate and I
have to aim it so that I don't have surface disturbance and so that it
doesn't dig a hole in the substrate. The Hygro continues to grow and
has sent down a number of fairly thick root fibers into the substrate.
The _stem_ of the plant however has rotted away for about 6 inches
from the gravel up. I don't know if this is related to the water flow.
Paul K and I have been speculating whether this is related to the
fertility of the substrate and caused by decomposition byproducts. I
wondered if this was not a natural phenomenon of the plant. Many
species of Hygrophila seem to loose small twigs which float on the
surface and might be a mechanism for propagation and dispersal.
I'm curious about other folks observations of H corymbosa and stem
melting of Hygrophila species in general.
Steve P in Vancouver BC