[APD] RE: Substrate thoughts

[Thomas Barr <tcbiii at yahoo_com>]

"Message: 1
Date: Fri, 21 Nov 2003 18:25:23 -0700
From: "Sharon Frey" 
Subject: RE: [APD] Some thoughts on substrates and some Heat cable
debate
To: "Thomas Barr" , "aquatic plants digest"


Tom,

Help me out here to understand. What I know is in nature the substrate any
plant grows in is not heated rather it is colder than the water or air it
grows into and that could also be true for aquatic plants. Thus the
principle of adding heat to aid beneficial biological growth has never
occurred in nature."
 
No it does occur, but not like the cable method, it happens via sunlight onto the substrate in shallow clearer waters, but the heat is from the top down.
 
Depending on the weather, the soil might be warmer than ther water column also.
 
On an ecosystem level, the influences of thermal heating by light on this substrate is likely very large is shallow lakes with large littloral zones such as many here in Florida and also almost all wetlands. This heating will increase the flux of nutrients in/out of the substrate and increase bacterial growth and reminerlization rates.
 
But I think it has less influnece on the plants themselves, the heat does not go down that far in most cases.   
 
 "Even the garden compost pile isn't heated. It creates
it's own heat for decomposing. As for aquatic mulm I save it for my
terrestrial plants and they thrive.
A new question: Is aquatic mulm the equivalent of land plant compost?"
 
Well it has less nutrients in it, a bit soupy also:)
 
 "I
question it's value if I have taken it from an aquarium that looks nutrient
deficient?"
 
Well, you want to add a few things to a new tank, bacteria, some organic matter(not too much though!) that will slowly decompose (peat and mulm are the two best substrances for this). This is what a mature substrate in an established tank has that a new tank does not along with definable layers of healthy stable bacterial and fungal colonies. 
The definable layer development  takes a bit of time, maybe a month or so to develop in good conditions, maybe 3 in so so conditions. 

This is where that balance ecosystem idea plays a role in a CO2 enriched plant tank, the substrate needs to be able to break down the particulate waste(mulm, fish waste/ plant detrital material etc) into the dissolved forms, the dissolved forms often need another break down to make them liabile and available to the plants either in the substrate or the water column. 
 
When there is high O2 levels from good plant growth, these bacteria and fungi work much better and plant growth is improved.
 
"Most thanks,

Sharon Frey
sharonfrey at earthlink_net"
 
Regards, 
Tom Barr





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