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Re: relevence of natural (open) ecosystems to tanks (closed)

Roger Miller wrote:

<< Compare that to our planted aquariums. Diana Walstad's ecologically
 principled aquariums have clear water with relatively calm currents and a
 very limited biodiversity.  They offer but two environments (soil and
 water) and a setting that is very unnaturally stable.  Water changes once
 every 6 months?  A natural stand of plants would see different water every
 few minutes!>>

This is a point many newbies, and even people like myself who should know 
better often overlook. With all the hype about "Nature Aquariums", and the 
pictures and ads for various "natural" products in aquaria mags, it's easy to 
be mislead if we allow it. Like it or not our systems are about as unnatural 
as they come. Personally, I wouldn't have it any other way.

For example: this total control of the water exchange can be used to our 
considerable benefit if we can but determine and tag certain variables and 
trace these to predictable outcomes. This is very much a work in progress, 
often right here on the APD.

This lack of water exchange may also, at some point, explain the 
preponderance of certain "undesirable" algae in some systems or the 
occurrence of what would appear to be some type of alleopathic phenomena in 

Mr. Miller further observes:
<< A more high tech tank may be run with more water changes and might (with a
 darkened sump and filter) offer more physical diversity, but biodiversity
 would still be low and all conditions would be closely controlled.  Don't
 even think of murky water, sinking detritus or suspended sediments!  
 Maybe adding fertilizers is a reasonable simulation of a deer or tapir
 peeing in the water.  Maybe not.
 There's really very little similarity between our aquariums and natural
 systems, and almost nothing from ecology that can be projected into our
 aquariums.  Observations from nature may give valuable clues about the
 physiology of some plants. Otherwise, information from the natural setting
 where a particular plant thrives is of little value because we almost
 never offer plants conditions that are anything like their natural
 environment. The natural environment in which our aquatic plants grow is no 
 relevant to most of our planted aquariums than the natural environment of
 wild squash is relevant to how you should grow zucchini in your garden. >>


Many of the common aquatic plant cultivars circulating in the trade, the ones 
we so often have in our own tanks, have been under commercial cultivation and 
perhaps more importantly, involved in selective breeding programs for so long 
that, like most Angels, Discus and Platies, any observations about the 
environmental preferences or requirements of their ancestors is liable to be 
of historical interest only.

There again, we do have some exciting new plant species which make an 
appearance every so often. Unfortunately - ironically even -- information on 
these can be frustratingly difficult to ferret out, especially if English is 
your only language.

Bob Olesen
West Palm Beach, FL