A few comments on the use of sand as a substrate for plants.
I bought a 100 pound bag of sand from the local hardware store for $4.
I believe it is usually used for making concrete. It is light greyish
brown and flecked, not blinding white like beach sand, and looks nice
and natural. It passed the acid test; I put some in a jar with water
and it did not change the pH. It was rather a chore to clean, and
took quite a few rinses. Now I have my tank set up with
sand/laterite/Tetra Hilena-D and am still seeing beautiful growth six
months after set up. (Several types of large and small swords, Rotala
indica, Hygrophila polysperma). An advantage is that the root systems
grow rapidly to enormous size. This is also a disadvantage, because
the bigger sword plants are impossible to move without disrupting the
entire tank. I just pulled up a huge Echinodorus cordifolius and made
quite a mess --it had roots 18 inches long. In the future I will
have to decide from the start where large plants will be permanently
located. Even small plants like E. intermedius or quadricostatus root
deeply and are hard to pull up without making a mess.
A possible disadvantage might be the lack of water circulation through
the fine particles. We will have to see what the long term stability
is. My feeling is that substrate heating coils would probably not
work well with fine sand.
When I originally set up this tank I put some sterilized peat and a
small amount of sterilized composted manure in. This turned out to be
a bad idea. In retrospect what apparently happened was that the
substrate went anaerobic and produced small amounts of H2S, which then
fed a bloom of single cell blue-green algae. (thanx to Shiao Wang for
help with this diagnosis). I battled this chronic cludy water
situation for several months, then gave up and tore down the tank.
If the tank is densely planted right from the start this may not be a
problem, but I would not be inclined to put a nitrogen source down
Someone (Erik, I think) mentioned that sand substrates are bad for
Corydoras, but I have not seen this. I have a shoal of Corys which
love to root about in the sand, and their whiskers are intact. Other
types of sand may have this problem, but not this stuff.
Sand does not need vacuuming the way gravel does, since detritus just
sits on top. Again this is also a disadvantage, as it does not hide
the junk, and can make things look a bit unkempt.
Right now I'm battling a form of algae which grows out of the sand in
green filaments with length a cm. or less. This stuff goes fairly
deep into the sand as well, and is very difficult to extirpate. I
don't have any Epalz. siamensis (SAE's), but neither Pleco (actually
Pterigoplicthys) nor Otocinclus care for it. It is very unsightly.
If anyone has comments on this nasty stuff I'd be most interested.
Up to the minute news: almost two weeks ago I put in some Crypt.
wendtii and pontederifolia, under a huge melon sword. Both types
started producing healthy new leaves within days. The pontederifolia
is now producing runners and sending up new plants amazingly quickly.
By contrast, I tore out a mat of Echinodorus intermedius and
replanted the best looking ones, a la George Booth. These are not
growing with anything near the alacrity I expected, and after two
weeks have yet to produce any runners. What might be happening here?
That's enough rambling for now.
A big round of kudos to Shaji and the others who started this list!
Regards to all
National Fish & Wildlife Forensics Laboratory
HoeschB at fws_gov