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Re: Substrates

>Date: Mon, 29 Dec 1997 16:35:49 -0600 (CST)
>From: eworobe at cc_UManitoba.CA
>
>These are the holidays! Chill

If you mean by "chill" that I should ignore what I believe is misleading 
information just because it's supposed to be a Happy Time, no, I'm afraid I 
can't do that. Sorry. 

However, I see where you took one of my comments personally and I apologize for 
inadvertently disparaging your time intensive and carefully controlled plant 
growth studies. 

Let me rephrase that particular part ...

Pushak quoted as Dave as saying:
>>>      "On the other side of the coin, there have been a plethora of
>>> studies which indicate clearly that rooted aquatic plants will not grow
>>> optimally on a sand or other infertile substrate no matter how richly
>>> you fertilize the water column (perhaps the earliest is by Pond, 1905)"

I said:
>>This doesn't jive with my experiences with massive plant growth using plain 
>>gravel substrates, undergravel filters and Dupla fertilizers. Just what is the 
>>scientific definition of "optimal"?  I hope it's more complicated than growth 
>>rates. Perhaps the researchers performing the plethora of studies just didn't 
>>know how to grow plants! 

OK, my interpretation was that Pushak included your quote to prove that you need 
a "fertile" substrate to have plants grow well.  I question this, in the context 
of the aquatic gardening hobby, based on my experience with what Pushak would 
call an "infertile substrate" with a well fertilized water column.  I have not 
run exhaustive studies as you have to define "optimal" growth of the decorative 
plant species I maintained in the tank, but they were growing fast enough that 
we had to prune their mass by 1/2 every two weeks.  For me, that was "optimal 
enough", non-scientifically speaking.  

My pointed remark about researchers not knowing how to grow plants was directed 
more to authors who write general hobbyist type books (like Rataj) than to real 
scientists doing real science.  

>From your comments, I suspect that you mean "infertile" in a more exact sense 
than Pushak uses, i.e., plain sand with nothing else - no fish waste, no water 
circulation to pull nutrients down to the roots, etc.  Is this correct?  I 
certainly have no argument that a substrate with no nutrients would not produce 
desired growth compared to a substrate with even a modicum of typical aquarium 
waste and detritus. It is obvious to me and I hope obvious to most readers that 
many plant species we maintain require nutrients in the root zone. Pushak and I 
seem to disagree on how much and how to get it there. 

If I am still off-base, perhaps we should try to define more carefully the 
varying types of substrates we use, going from an impratical to achieve 
"sterile" substrate to the full on organic cesspool. There is clearly a range of 
substrates that work very well in an aquatic gardening environment and we need 
to be able to accurately describe the various types without resorting to 
pointless and unverifiable "this works better than that" claims.  

Happy Holidays,
George