Using Lava Rocks
To Remove Nitrates from Aquarium Water. Click
here now to buy
a bag of Lava Rocks.
aquarium and fish bowl should contain the appropriate
amount of Lava Rock, which provide the ideal
living environment for beneficial denitrifying
bacteria. These bacteria will remove nitrates
and greatly improve the quality of the water.
to buy a bag of Denitrifying Lava Rock, like
one shown just above .These Lava Rocks are very
porous, which allows the aquarium water to diffuse
through the rocks. As the water passes through
the rocks, beneficial nitrifying bacteria consume
all the oxygen in that water to produce an anaerobic
environment inside these rocks.
In this anaerobic
environment denitrifying bacteria consume nitrate
and produce oxygen and nitrogen. More than 40-parts-per-million
of nitrate in aquarium water is not good for
most types of fish and aquatic invertebrates
like crabs, shrimps, and lobsters. These Lava
Rocks are the best way to remove the nitrate.
a beautiful Gold Line Corydoras Catfish swimming
between some pieces of Lava Rock on the bottom
of one of our aquariums. We have Lava Rocks
like these in all of our aquariums and fish
an African Dwarf Frog living in an aquarium
with several pieces of Lava Rock that always
keep the nitrates low, which is very important
for frogs. Click
shop online for African Dwarf Frogs.
a Red Sakura Shrimp loves to examine
Lava Rocks for tiny bits of food to eat.
shop online for Red Sakura Shrimp.
Lets Start over at the Beginning.
You feed the fish
in your aquarium or fish bowl, and much of that
food is converted into ammonia in the fish's
waste. Ammonia is very toxic to fish and must
be removed. Beneficial nitrifying bacteria combine
ammonia and oxygen in the water to produce nitrite,
which is still very toxic to fish but usually
not as toxic as ammonia. So this is an improvement
in the water quality!
Next another type
of beneficial nitrifying bacteria combine that
nitrite with more oxygen to produce nitrate,
which is still toxic to fish in concentrations
of more than about 40-parts-per-million, but
less toxic than the nitrite. So this is another
As aquarium water
diffuses through Lava Rocks, beneficial denitrifying
bacteria, living inside the lava rocks, convert
the nitrate to oxygen and nitrogen, which are
both harmless, and this completes the process
of converting very toxic ammonia to non-toxic
oxygen and nitrogen.
For a Long Time
including the Bailey Brothers, were told that
nitrate dissolved in aquarium water was harmless
to fish, but we've now learned this is
not true. Nitrate in concentrations above 40-parts-per-million
is harmful. The best way to control nitrate
is to have the right amount of Lava Rock in
your aquariums and fish bowls.
Where do you put
the Lava Rocks?
The Lava Rocks
must be in the aquarium water. You can use them
as ornaments. They look natural and pretty good.
They do not need to be in an aquarium filter.
Will any old Rocks Work?
No! Rocks may
contain insect sprays and other toxins that
are very poisonous to fish. Some types of rock,
including many types of Lava Rock, contain minerals
that are not good in aquariums. Even if the
rock is non-toxic, it also needs to be porous.
Most Lava Rocks are porous, but some are glass
lava and not porous, so they won't work to reduce
nitrates in aquariums.
The Lava Rocks
shown at the top of this page have been carefully
chosen and tested to produce many good results
and few bad results. Of course, as with any
natural material, something could occasionally
Can the Nitrate get too Low?
Yes! If the concentration
of nitrate in aquarium water gets very low,
yet another type of bacteria can begin to produce
hydrogen-sulfide, which is extremely toxic to
fish. So ideally it is probably best to try
to keep the concentration of nitrate between
about 20 and 40-parts-per-million.
How to Test for
We use Aquarium
Water Test Strips, shown in the picture just
above. They are rather inexpensive, seem to
be pretty accurate at least accurate enough,
and they're quick and easy to use.
Just take a
small strip out of the container, dip it in
aquarium water, and the colors on the strip
indicate the amounts of ammonia, nitrite, nitrate,
and the pH of the water. Click
here to learn more about these Aquarium
Water Test Strips.
If your Nitrate
goes too Low.
If you test for
nitrate, using the Aquarium Water Test Strips,
and the reading is below 20-parts-per-million,
we recommend removing some of the Lava Rocks,
then wait a few days and test again. If the
nitrate is still below 20-ppm, remove some more
of the Lava Rocks.
amount of Lava Rocks in your aquarium until
the nitrate is between 20 and 40ppm of nitrate.
This is really kind of fun, not much work, and
will greatly improve the water quality in your
Lava Rocks in
a Fish Bowl?
Yes! Every fish
bowl should have a nice piece of Lava Rock,
which is kind of decorative and will greatly
improve the water quality in the fish bowl.
One piece of Lava Rock is usually enough.
Just like with
an aquarium, you should test the water in the
fish bowl with Aquarium Water Test Strips, then
adjust the amount of Lava Rock, which may require
you to break a piece of Lava Rock into smaller
pieces and put a smaller piece of Lava Rock
back in your fish bowl. It doesn't take much
Lava Rock to reduce the nitrate in a fish bowl
to a safe concentration.
The ad below links to this advertiser.
Lava Rocks in
Yes and no. First
test the water in your pond, using Aquarium
Water Test Strips, mentioned above on this page.
If the test strips show nitrate is below 20-ppm
or above 40-ppm, you should take action.
Above 40-ppm you should add some Lava Rocks
to grow the beneficial denitrifying bacteria
that will remove the nitrate. Below 20-ppm you
should investigate or seek help with your pond's
water quality. Because with very low levels
of nitrate another type of bacteria may start
to produce hydrogen-sulfide, which is very toxic
to all fish.
Lava Rocks in Saltwater Aquariums?
Saltwater aquariums usually have other ways
of dealing with nitrate, such as live rock and
deep sand beds.
to hear the special
by DrTom and Nevin Bailey about
denitrification of aquarium water.
here to hear the
discussion by DrTom and Nevin
Bailey about aquarium water quality.
Hello Bailey Brothers!
While I wait hopefully
for a new show I thought
I would take this moment
to ask a question about
Lava Rock. I went to
Lowes and picked up
a bag of red Lava Rock.
Soaked it for about
a week until most of
the sediment was gone.
I have a colleague who
let me experiment on
his tank (ok ok I was
too chicken to try it
in mine) He has feeder
goldfish and is not
terrible attached to
them. I however am very
attached to my fish
So I first tested his
water and noticed that
his ammonia and nitrates
were off the charts.
I quickly told him to
do some waters changes
to get that under control.
I went ahead and dropped
a few rocks in his tank
to see what would happen.
I have tested his water
every day for about
2 weeks weeks with no
real change in his nitrates.
They are about 100ppm.
So I decided to take
some of my water and
put it in a bowl with
some of the Lava
Rock to see if I would
see any changes there.
I don't really know
if this is a good experiment
or not. I have just
tested the water and
the Nitrates are high
Is there something I
am doing wrong? The
bowl maybe has a cup
of water and about 13
pieces of small red
Lava Rock. Thank
you for all your help
and everything else
you do. Hopefully
you guys are not hanging
up your hats on the
show. Take care
and fish on!
Jose From Maryland
Jose and thank you for your interesting email.
We think the Lava Rocks that you're testing
probably don't yet contain enough of the beneficial
denitrifying bacteria. It may take many
months for the bacteria to colonize your Lava
Rocks, and that's one reason that we recommend
ONEdersave's Eco-Bio Products, which are made
of Lava Rock that are already seeded with the
denitrifying bacteria. Click
learn more about Eco-Bio Products. We have ONEdersave
products in each of our personal aquariums,
but we also use Lava Rock, like those that you
bought, in the aquariums in our business. However,
apparently we were lucky and got Lava Rock that
was already seeded with the beneficial denitrifying
bacteria. How did that happen?
Well the Lava Rock that we bought must have
been extracted from a place that had been exposed
to water like a riverbed, where that Lava Rock
was populated with denitrifying bacteria.
It was a big surprise
to us, when the nitrates in our water began
to immediately decline. Otherwise we would have
had to wait, until the denitrifying bacteria
colonized our Lava Rocks. By the way you
want to keep the nitrates in your aquariums,
fish bowls, and ponds between about 20ppm and
about 40ppm. So 100ppm is high, but not really
extremely high. Before we began using Lava Rocks
in all of our aquariums and aquarium systems,
our nitrates often tested at 160 and higher, which
is dangerous for almost all fish. When we added
Lava Rocks, the nitrate came down in a few days
to right about 20ppm. Our Lava Rocks worked
like a miracle, but as we stated, we were lucky.
Once your Lava Rocks become populated with denitrifying
bacteria, your nitrate should come down to about
20ppm like ours did. Where do you get some
denitrifying bacteria to begin the colonization
process in your Lava Rocks. There are some in
every aquarium, fish bowl, and pond, but it
takes a while for them to migrate to your Lava
Rocks and then begin to multiply, until eventually
there will be enough of them to reduce the nitrates
in your aquarium water. This can take
as long as many months. That's why we recommend
the ONEdersave Products, which begin to work
here to shop online for Eco-Bio Stones now.
If the ammonia
in your aquarium is also high, as you mentioned
above, then it needs to be digested by nitrifying
bacteria, which are usually different from the
denitrifying bacteria. The best way
to do that is with a Bio-Wheel filter, as we've
mentioned during many of the Pet Fish Talk Shows,
and the Eco-Bio Stones will also help with the
nitrifying bacteria that grow on the surface
of those Stones. The denitrifying
bacteria live in the interior of the Stones,
where the oxygen is low and so they use nitrate
as an oxidizer instead of oxygen. Perhaps we should
mention here that ONEdersave does not advertise
their products for denitrification, though they
may mention it on their web site. They recommend
their products as a safe haven for nitrifying
bacteria, but we know that their products work
for both nitrification and denitrification,
and both of these processes are very important
in aquariums. Thanks again for
your interesting email.
My name is Bill and
I was interested in
some info about lava
rock and denitrification.
I am trying to determine
how much lava rock per
gallon to use and if
the size of each rock
matters for denitrification.
I have a 135 gallon
aquarium and a 90 gallon
sump. My goal is zero
Thanks for you help
Bill, thank you for your email. We don't know
of anyway to calculate or estimate the amount
of lava rock to use. But here's what we do.
First, we test our aquarium water for nitrates
using an inexpensive test strip. Click
information about these test strips, which seem
to be accurate enough for this project.
If the nitrates
test between 20 and 40 ppm, then you don't need
to do anything. If the nitrates are a little
bit above 40 ppm, you might change 20% of the
water and retest. Maybe you just need to do
more partial water changes. If your nitrates
remain too high above 40 ppm, then add some
aquarium-safe lava rocks, and retest in a few
days. Keep testing
and adding or removing lava rocks, until your
nitrates are between 20 and 40 ppm. By the way
sometimes the lava rocks will start removing
nitrate in a a couple of days, but sometimes
it takes several weeks. Why? If the lava
rocks already contain plenty of denitrifying
bacteria, those bacteria will come out of stasis
in a couple of days and start removing nitrates.
On the other hand if the lava rocks do not contain
plenty of denitrifying bacteria, they will need
to start invading the lava rocks and slowly
multiply before they can reduce the nitrate
in the aquarium water. This is sort of
analogous to establishing the nitrifying bacteria
in an aquarium. You mentioned
that your goal is zero nitrates, but this is
dangerous! It's good to have zero ammonia and
zero nitrites, but not zero nitrates, because
zero nitrates will encourage bacteria in the
lava rock to start using sulfates as an oxidizer
and producing hydrogen sulfide, which is very
poisonous to fish. The presence of 20 to 40
ppm of nitrates inhibits the production of hydrogen
keeping nitrates between 20 and 40 ppm is very
important to almost all freshwater fish.
I hope this information
helps you and your fish.
I watched a video on
Youtube that was selling
a big device that removes
nitrate from aquarium
water. The device had
lots of adjustments
and required adding
vodka - yes vodka. The
video also said it was
very good because it
reduces nitrate to 0,
as in none.
All of this is quite
different than your
advice, and I just wonder
if your method with
lava rock, which costs
a lot less and is much
easier, will work as
Reply. Hi Bubba, and
thank you for your email. Actually over the
years we've seen lots of these devices and even
All the ones we bought were very expensive,
very complicated, and required lots of adjusting.
Plus they did not work as well as the Lava Rock,
which require no adjusting at all!
Unfortunately there is lots of really bad advice
about aquarium equipment, and using a device
to lower nitrates to 0, as in none, is one of
the worst pieces of advice.
As mentioned above, if an aquarium has 0 nitrates,
then other bacteria will begin to convert sulfates
into hydrogen sulfide, which is very poisonous
and smelly. From time to time I've been able
to smell hydrogen sulfide from an aquarium,
and the fish in those aquariums all looked poor.
Lava Rock is cheap,
works great, and is adjustment and maintenance
free. It's like a miracle. Very important to
the health of your fish. So just get some and
pop it into your aquarium, while keeping your
money in your pocket and the vodka in the bottle!
A Criticism of
to read a criticism of the advice we give above
on this page about using Lava Rock in Aquariums
to reduce nitrate.
seems to be (1) it's better to have 0 nitrate,
and (2) you can buy a much bigger bag lava rock
elsewhere and pay more but much less per pound.
A few years
ago I began to learn that maybe natural aquatic
environments have nitrate, and I knew that all
fish are pretty well adapted to the natural
water that they live in. So I began to think
that maybe it was possible that nitrate is not
always bad for fish.
a very highly respected, perhaps in fact the
most highly respected, aquatic chemist, who
has a PhD from one of the best universities
in that field, and who has advised many professionals
in the aquarium business for many years.
said, that all aquatic systems with very low
levels of nitrate will start to produce hydrogen-sulfite,
H2S. And that this fact is well known to all
aquatic chemists, like himself.
that in aquatic water with lots of oxygen, the
oxygen-using bacteria dominate. In water without
oxygen, nitrate-using bacteria dominate. And
in water without either oxygen or nitrate, sulfate-using
bacteria use sulfate as an oxidizer and convert
the sulfate into H2S, and even very low amounts,
or concentrations, of H2S are very detrimental
to all fish.
a concentration of H2S is detrimental? Much
less than one part per billion, and probably
concentrations that are undetectable by aquarists.
with the opinion of perhaps the best professional
source vs. the opinion of 100-aquarists, who
think they've never had a problem.
given at the link at the beginning of this section,
is the sort amateur advice that is invalid and
hinders hobbyists, who are trying to advance
their knowledge, which should be based on real
So we stand
by our comments that keeping nitrates above
0 is very important. We still recommend a range
of 20 to 40 ppm, and we are still very confident
in our advice.
On to the second comment
about charging too much for lava rocks.
There may in
fact be larger bags of lava in big box stores
that may cost much less per pound.
The lava we
sell is about the right amount for many aquariums
and is tested to be aquarium safe. Why pay more
for a big bag that may not be safe for your
fish, when all you need is a small bag that
We have never
pushed any product, such as lava rocks or test
kits, to make money. All of the advice on this
web site is written to help aquarists and their
As far as we
know, we were the first aquarists to stumble
onto this whole story about nitrate and begin
to spread this information to other aquarists.
We think this
shows that we're on the leading edge of aquarium
knowledge. But as stated above this story about
nitrates has been very well known to professional
aquatic chemists for a long time.
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