Re: [APD] old soil substrate

["S. Hieber" <shieber at yahoo_com>]

Based on Walstad's excellent treatise, doesn't it take many
years for the soil to be depleted?

Aren't soils from diff places very diff?

Scott H.
--- Jim Seidman <js5 at seidman_net> wrote:
> josh bjork writes:
> "I've got a soil substrate based tank that is a year or a
> year and a half
> old.  It's 50gal and I used maybe a coffee can full of
> soil under poultry
> grit.  It had a very nice growth spurt when the roots hit
> the soil.   The
> growth has curbed significantly.  I have a medium fish
> load and give it
> potassium occassionally."
> 
> "My smaller 20 gallon soil tank with 1 algae eater looks
> fabulous with no
> care at all.  The tank has been running with no
> circulation for 6 months or
> so.  What causes this fizz?  I would think the tank with
> fish would have
> much more growth than one with an unfed algea eater."
> 
> With all due respects to Karen, I don't think the issue
> is inherent
> unpredictability of soil substrates. Rather, my guess is
> that the 50g has
> not nearly enough soil to support the plants.
> 
> One coffee can full is not much soil. In my tanks I
> generally use a 1 to
> 1.5 inch layer of soil on the bottom. This provides a
> huge store of
> nutrients. 
> 
> Your 20g tank may have a thicker layer of soil, or simply
> less
> nutrient-demanding plants. However, if you prune, you can
> be guaranteed
> that the tank will eventually run out of nutrients as
> well, since you'll be
> removing them from the tank without adding new ones.
> 
> Do you have a nitrate test kit? I have found that despite
> generous feeding
> my macronutrient levels tend to plummet. Nitrate is a
> particular problem
> because soil is a great medium for denitrifying bacteria.
> Regular dosing of
> KNO3 and NaH2PO4 has made a huge difference. You might
> need to do the same.
> 
> Soil in sufficient quantities can provide enough traces
> to last for many
> years. It can potentially provide enough macronutrients
> to last for a
> while. Given the small quantity you used, I think you
> simply depleted it.
> 
> - Jim
> 
> 
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=====
S. Hieber

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