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Re: Substrate idea and water quality questions

James Purchase writes:

> The web-site you refer us to appears to be a mini-infomercial for this
>  stuff, and should, IMO, be taken with a grain or two of salt (or a few 
>  of what a lot of hydroponics growers specialize in).<snip>

But I can't find any of this clay for sale on their web-site.  Maybe it's 
there and I missed it.  And what hydroponics growers specialize in is growing 
terrestrial plants in an aquatic environment.  I still think they must have 
something to offer us since we are using the same basic medium.

>  Clay in a substrate does help to bind nutrient ions until they can be
>  absorbed by plant roots. I don't like the idea of the presence of almost 
>  aluminum in this stuff - that could present you with toxic conditions once
>  submerged. Dupla, in their many writings on laterite, stress the fact that
>  laterite is a type of soil which has has most things (which could present
>  problems) leached out of it.

But one of the things that is not leached out of laterite, as I understand 
it, is the aluminum.

>  One possible senario which might prove both interesting and valuable would
>  be to set up two tanks, one using Substrate Gold (you said that you've used
>  it in the past, maybe you have some left) and a second using this
>  pyrophyllite clay. Get a group of plants (hopefully, all from one source)
>  and take a representative sample and submit it to a lab for elemental
>  analysis (see Steve P.'s web-site for references) and then plant both tanks
>  with the rest of the plants. After about six months to a year, take similar
>  plant samples from both tanks and submit them for the same analysis to the
>  same lab. A comparison of the elements found in each of the samples coupled
>  with the growth patterns you observe in the individual tanks could prove
>  interesting to a lot of us.

Or maybe I could just grow some plants in the stuff and see how they do.  If 
I want to get all scientific with it, I'll pop the tuition and go back to 
school.  I'm trying to have fun here, remember?

>  As far as your water quality report, I suspect there might have been a
>  mistake made:
>  > Silica (as SiO2 ) 42.2 mg/l ; Color (whatever that means) 8.0mg/l
>  Are you sure that they report Color using mg/l? Color is usually reported 
>  T.C.U. (True Color Units). If your municipality is capable of making a
>  mistake like this, I'd suspect the rest of the numbers they report as well.

This is a small town, with small town ways.  Last year the color was reported 
in TCU, but the secretary for the water dept. had a baby.  The new secretary 
probably got cruising along and didn't notice.  I didn't think about it, or I 
would have corrected it myself.

>  Toronto's water comes in at 1 TCU, and the provincial operational 
>  for water suppliers calls for this parameter to remain under 5 TCU. But it
>  is not a healt related issue, merely aestetic.
>  > Now, mind you, some folks on this list keep fish in their tanks for the
>  sake
>  > of providing food for the plants.  I, on the other hand am trying to grow
>  > plants to keep the nitrates and algae under control, and my fish a Amazon
>  > drainage soft-water critters.  This means I don't want to get too much Ca
>  or
>  > Mg or CO3 in my tanks, and I would like to keep conductivity down, which
>  may
>  > be difficult when providing for the needs of the plants.
>  If you are trying to create a blackwater biotope (or even a whitewater
>  biotope) as would be found in the Amazon Basin, why not just bite the 
>  and get yourself a R/O filter. That will strip pretty much everything out 
>  your source water and allow you to re-create it to match your ideals
>  exactly. Much simpler than in trying to deal with what you've got. But
>  remember that plants do need both Ca++ and Mg++.

Which is part of the reason I don't want to strip this stuff out.  The other 
part is that I am renting a very small duplex and sharing it with my four 
kids.  There really isn't a lot of room for dealing with such a set-up.  And 
if I can avoid the waste-water issue, all the better.  This is the West, not 
the Great Lakes Drainage, and water out here is precious.

> In nature, even though the
>  water column might be very deficient in these mineral ions, there is so 
>  water flowing past the plants that they can get enough for their needs. The
>  same does not necessarily follow in an aquarium, due to the difference in
>  scale. You might have to bump up the Ca++ and Mg++ in your tank in order to
>  obtain good plant growth. Many folks on the list report having to use extra
>  calcium carbonate to get good plant growth, even in moderately hard water.
>  I don't know how many submerged aquatic plants live in the typical
>  blackwater biotope in nature.

Precious few, if any.  But there are many moving bodies with plants in them.

> Perhaps one of the folks who took the Amazon
>  Trip could report (on true aquatics, not on submerged terresterial plants).