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 L# General Freshwater
  L# Sand vs. pebble/rock
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SubscribeSand vs. pebble/rock
Small Fry
Posts: 5
Kudos: 7
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Registered: 25-Mar-2012
male usa us-colorado
so this should get some interest back into the forums . what should we use in setting up a fresh water aquarium shall we use sand as sand wont let the bi products or food collect down in rock like when we use the normal pebbles. and which sand to use, because some sand will raise the ph scale and others are tuned to growing algae fast. there are a lot of pros and cons, what are your opinions?
Post InfoPosted 26-Mar-2012 09:12Profile PM Edit Report 
Posts: 5108
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Registered: 28-Dec-2002
male usa us-colorado
EditedEdited 27-Mar-2012 14:03
Hi and Welcome to Fish Profiles!

Probably, the worst substrate consists of pebbles or
the small polished pebbles, or marbles. These, when used
as substrates, allow all sorts of detritus to settle in the
large gaps between them and there they rot and pollute the

Normal aquarium gravel is a #2 or #3 size grain.
provides a good balance between appearance, and the needs
of the plants to give them a place grow roots to anchor the
plant and a nutrient sump for the roots to draw from.

Sand can be used as a substrate, but with it comes a
variety of problems that with attention can be overcome.

The general depth of a substrate should be between 3 - 4
inches. If you use sand, that deep, over time, it will
compress itself, and the bacerial film that grows around
each grain will close off any circulation and form a
barrier between the upper half inch or so of the bed and
the lower reaches. This will create an anaerobic area
within the bed that is toxic to the aerobic bacterial
colonies that live within the substrate and also kill
off the roots of the plants.

Most folks choose sand for its resemblance to the "white
sunny beaches" It can really look nice, and some use it
to form features, such as a "stream" running through a
darker substrate. Another problem is that sand, over time,
will stain and discolor due to any iron in the water, and
some organic compounds that are created in the water
through the breakdown of waste products. Even with
constant maintenance, the sand will gradually loose its
"nice" white color and have to be replaced.

Another problem with sand is that with the bright
color, very small grain size, and very small gaps
between grains, any solid waste will become obvious
and it needs constant cleaning to, well, keep it clean.
The bright white color will reflect the light, and many
fish will remain huddled under something that gives them
shade, or some object that will shield them from any
flying predators. For some, it is simply too bright,
and they stay in the shaded portions of the tank.

Sand is Silica and sand can cause outbreaks of diatoms,
(commonly called "Brown Algae." These single cell critters
actually thrive on the silica floating around in the water
(it's a real banquet for them) and it can give way to
an amazing agal bloom. Great food for baby fish, but a
real headache for the hobbiest.

Sand can be a problem when trying to grow some plants.
Because of the small grain size, there is not enough "weight"
to hold the plant down and they constantly break
free and float to the surface.
It's good for small foreground plants but larger
plants can become problematic.

Another problem with sand, due to its small grain size is
that it is easily disturbed. Fish suddenly changing
direction, water changes, and cleaning can cause the
grains to float up into the water column
where currents can carry them around the tank and they
are sucked into the filters where they will easily
grind up the impeller blades of the filter pump.
You can resolve this problem by keeping intakes high
up in the water column instead down closer to the substrate.
Also, wrap a piece of sponge pad around the filter intake
and secure it with a couple of rubber bands. This forms
a "prefilter" that will keep the grains of sand out of the

It's hard to clean sand. The siphons, such as the python
style, will empty the tank of sand in a heart beat, where
with regular aquarium gravel it will just swirl around
in the intake tube knock off any clinging detritus to be
carried off, and the cleaned gravel will settle back down
to the bottom of the tank.

If you are going to use sand, then I would not use more
than an inch for the substrate thickness. Use
foreground to mid tank plants, house some corry catfish,
and/or the MTS burrowing snails in the tank to keep
the substrate "loose" and aerated.

One can purchase aquarium gravel that is inert, and is
actually quartz. You can purchase sand that varies from
beach white through shades of brown, to jet black. for the
most part, these are all varieties of quartz
(Silicon dioxide, SiO2).

To increase the hardness and pH of the water you can use
any substrate that is a carbonate. Substrates such as
crushed coral, dolomite, or limestone will all dissolve
in the water and bring your pH into the "8s" and increase
the hardness into "liquid rock" perfect for Rift Fish,
live bearers, and such.

Some rocks, when put in the water will do the same.
Collecting rocks for the tank can be great fun, and can
also cause problems. When collecting rocks for the tank
in the wild, you must scrub them well with a good stiff
brush and wash them to remove any dirt, roots, and
"critters" that might be living on them. Then take a
pocket knife or something to scratch the surface and
scrape off a small piece of the rock to get rid of the
weathering. When you have a fresh surface exposed place
a drop or two of vinegar on the newly exposed surface.
Vinegar is a weak acid (acetic acid) and if the rock is
a carbonate, it will give off bubbles (fiz). If you are
concerned about your pH, then do not use the rock if it
fizzes. If if does not then chances are it will be just
fine in the tank. Don't use any rocks that have iron in
them or especially copper.

Some substrates are "plant friendly" in that they have
nutrients in them that are like time release capsules.
These feed the plants over time. The problem is that the
"over time" is generally about a year, and after that, all
the nutrients have leached into the water and then they
become just like any other substrate, just something for
the plants to anchor themselves in. One exception to
that is the various clays, such as Laterite and
SeaChem's fluorite. This is an iron rich clay that
the plants can draw on for their iron needs from for
years and years.

Substrates for planted tanks should be 3-4 inches thick
and generally should be a #2 or #3 grain size. This
gravel and grain size will allow you to grow virtually
any size plant from tiny foreground plants to tank
busting plants like jungle val and huge amazon swords.
If you aren't going to grow large plants then you don't
need that kind of depth and one to two inches would be
Sand can be a problem but use a shallow bed no more than
an inch thick. Keep it clean, and aerated.
Any of the plant friendly "soils/substrates" are designed
specifically for plants and encourage their growth. Some
last for years, and others peter out after 6 months to a
By themselves, pebbles and marbles are not a good substrate
plants will be stunted, if they grow at all, and that
type of "bottom" is a septic tank in the making.

Hope this helps... There are all sorts of books and
hundreds of articles that have been written on the
subject. Do some research...


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--
Post InfoPosted 27-Mar-2012 07:25Profile PM Edit Delete Report 
Small Fry with Ketchup
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Registered: 17-Apr-2003
female australia us-maryland
Even having done all my research into using sand I still had a long series of unfortunate events () with it. Won't have sand in any tank again because of it. We have regular aquarium gravel in all of ours now.


Post InfoPosted 27-Mar-2012 23:06Profile Homepage AIM MSN PM Edit Delete Report 
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