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Re: Sand (was Aquatic Plants Digest V4#823)

Dear Paul,

As Ivo and Lobos have said, sounds pretty complex to me!  I am using two 
layers, one potting soil (already has peat in it) with a bit of extra dolomite 
for calcium, as my water in Vancouver is very soft, plus Profile/Shcultz's 
Aquatic Soil, which seems to be working well for me.  You don't need gravel on 
top of the Profile, it is already in gravel form, and does not weep or 
anything like ordinary clay/art clay/kitty litter/laterite would.  The Profile 
gives you the clay component; others combine laterite etc instead with sand or 
gravel or whatever for the same effect, with the sand/gravel being there to 
keep the water clear.  If you are keeping soft water fish, maybe add some 
extra peat; if keeping guppies/platies like me, harder water is better.  The 
Profile pH is 7.0.

For the other part of the substrate, I don't think anaerobic areas are 
necessarily bad - read Diana Walstad's "Ecology of the Planted Aquarium", she 
has experimental evidence that shows plant roots go all through it, and that 
is the case in my tanks.  It depends on whether you are going high tech, with 
under-substrate cables, CO2 and lots of light and nutrients to force a fast 
growth rate, or if you are doing it slower, like me, with less light and no 
substrate heating - steady but not rampant growth is my aim.  I have heard a 
lot of people say sand compacts too much; I haven't found that soil compacts 
too much, in fact, if you go that route, you need to make sure that you sieve 
it to take out all coarse material, and try to compact all the air out of it 
when you put it into the tank.  I would also soak it for at least a week to 
get rid of the initial volatility, after that, it is fine, but read Diana's 
book first if you can.  So think about how much work you want on an ongoing 
basis (plus expense of all that equipment!), and look up substrates on the 
Krib (http://www.thekrib.com), also the APD archives, lots of food for thought 

I would not think that cheesecloth or anything else would work to separate the 
layers - fine clay or soil particles would leach through cheesecloth, and the 
layers will be a pain when it comes time to move a plant, especially once the 
roots go through it.  If you have fish that like to root around in the 
substrate, you might have to have sand for Corys; or use gravel/Profile as a 
top layer - the one snag with the Profile in that case is that it is pretty 
light, and shallow rooted plants might have to keep being replanted.  Diana 
says that with time, bacteria bonds to any fine clay/soil particles, so that 
any disturbance means the water will cloud, but the particles quickly settle 
out again, and that has been my experience.  If I have pulled up a lot of soil 
from the substrate when replanting, I just add an extra handful of Profile / 
gravel to the surface there, it covers it up again.

Re the addition of Jobes spikes etc, you need to add some nutrients for the 
plants somehow - if it is just plain gravel or sand, the plants get it from 
the water, the fish poop, the mulm that takes time to develop, or stuff you 
add to the water column, which is a great way to grow algae IMO.  If you plant 
things in soil, you are mimicking a natural environment and providing the 
plants with at least an initial burst of food.  When that food is exhausted 
(takes a year or two with soil substrates depending on depth), you can add it 
to the substrate by using Osmocote/slow release fertiliser pellets inside clay 
balls poked down as far as possible, or just straight pieces of Jobes sticks, 

I'm an Aussie, we like to do natural gardening - we don't rake up/blow into 
neat piles and dispose of every dead leaf in the fall like Americans tend to 
do, it makes good fertiliser and mulch for the plants.  Likewise, I don't see 
the need to suck up every bit of mulm with a gravel cleaner, its good plant 
food.  And snails make good recyclers to transform waste into the form plants 
can use.

Whew! that was a long one, I've got off the soapbox, hope that helps,

Susi Barber