DIY Coil Denitrator (Step by Step walkthrough with pics)
- Thread starter elgenyo
- Start date
Taken from thekrib.com becuase I'm lazy and didn't want to put it in my own words...lol
The basic coil denitrator is a long section of small diameter tubing
with a slow flow of oxygenated water containing ammonia, nitrites and
nitrates, i.e., normal aquarium water. Aerobic bacteria naturally
colonize the insides of the tubing and transform ammonia to nitrite
and nitrite to nitrate. This process uses up the dissolved oxygen in
the front section of the coil and produces anaerobic conditions in the
rest of the length. Anaerobic forms of bacteria grow in this area
and reduce the nitrates and nitrite to gaseous nitrogen.
The trick in the setup is to pick the correct tubing size and length
and proper water flow such that enough bacteria of the right type can
develop and have enough time to complete the denitrification cycle.
Safety and efficiency concerns direct the actual design of such a
system.
The coil is simple to make from readily available materials. A visit
to a hardware store or nursery that carries drip irrigation supplies
will provide you with the basics. Fifteen to twenty-five feet of the
thin-walled black, 1/4" PVC tubing used for drip irrigation is perfect
for this application. Simple connectors are available that allow you
to attach the tubing to a source of water. This will generally
produce too much water flow but an inexpensive 1-4 gallon per hour
(GPH) valve is also available that allows for fine adjustments of the
water flow.
For optimum operation, the water should be mechanically but NOT
biologically filtered before entering the coil. This prevents
water-born particles from clogging the small diameter features of the
coil while supplying the maximum amount of ammonia and nitrite to the
aerobic bacteria. Unfortunately, this is difficult to accomplish in
practice since any mechanical filter media will also become a
substrate for nitrifying bacteria. A good compromise is to use the
water return of a canister or trickle filter as the source of water.
This water is very clean yet has been proven to provide enough "food"
for the bacteria.
For safe operation, the outflow from the coil should be passed through
a biological filter of some kind. At some point during the startup
period of the denitrator, enough bacteria will be present to reduce
nitrate to nitrite but not enough to take it all the way to gaseous
nitrogen. It is also possible that after being established, something
may happen that would disrupt the denitrification cycle and nitrites
could again be generated. You do not want to return this nitrite
laden water directly to the aquarium.
APPLICATION
Two of our large 90 gallon freshwater aquariums are heavily planted
and well stocked with fish. Even with the lush plant growth, we had
to change significant amounts of water to maintain low levels of
nitrates. Prior to implementing the coil denitrators, we were
changing 50% of the water every two weeks. This was time consuming
and quite expensive due to the water conditioning and plant fertilizer
products that we use.
Both of these aquariums have trickle filters which allowed a very
simple coil denitrator system. A hole was punched in the vinyl water
return line to the aquarium with an inexpensive drip irrigation hole
punch designed for this purpose. The water return line passes over
the trickle filter sump at the point the hole was punched so if any
leakage occurs it will harmlessly drip into the filter. A 1/4" right
angle connector pushed into the hole connects one end of the coil to
the return line. The back pressure from the 4 foot head is sufficient
to provide more than enough flow through the coil.
The small 1-4 GPH valve is put at the outlet end of the coil. The
valve clogs easily so it is best to put it on the outlet side of the
coil for easy periodic cleaning. A short piece of 1/4" tube is
attached to the other side of the valve and fits into a small hole
drilled in the filter drip tray cover. The water from the coil thus
passes back through the trickle filter providing insurance against
toxic nitrites. The coil outlet is a loose fit in the cover so it can
be easily removed for cleaning and monitoring water flow and nitrate
concentration.
The coil itself rests on the PVC plumbing coming from the filter pump.
It is not fastened down so it can be easily moved if access to the
plumbing is required.
Once set up, the water flow through the coil can be measured by timing
how long it takes to fill a container of known size. For example, if
it takes 6 minutes to fill a 500 ml container, the water flow is 5
liters per hour. Water flow should be checked regularly since
bacteria and their waste products will build up and restrict the coil
and valve. The valve can easily be removed and cleared by blowing
through it but the coil should be left undisturbed. We have found
that the flow through the coil itself is usually not impeded enough to
affect the operation and any attempts to clear the tube will probably
result in a disruption of the denitrification cycle.
The system takes 4-6 weeks for the aerobic and anaerobic bacteria to
completely populate the coil. Prior to this point you may find some
nitrite being formed if you have a sensitive test kit.
Once the coil denitrator is established, the nitrate reduction will
depend on the flow through the coil and what percentage of the coil
contains anaerobic bacteria.
RESULTS
In our set up, we use 15 feet of 3/16" ID tubing and have a water flow
of 3 liters per hour through the coil. The most recent nitrate test
with a Lamotte low range nitrate test kit showed 1.0 ppm
nitrogen-nitrate (4.4 ppm nitrate) on the input and 0.75 ppm (3.3 ppm)
on the output. With a reduction of 1 ppm (1 mg/l) and a flow of 3
l/h, the denitrator is removing 3 mg of nitrate per hour. This is
keeping up with nitrate production since the overall nitrate levels in
the aquariums are staying at around 4-6 ppm. There is no nitrite
coming from the coil as verified by a Lamotte nitrite test kit.
Note that the effects of the denitrator can only be seen if the
nitrate concentration of the inlet water is very low since the
resolution of test kits available to the hobbyist varies with the
nitrate levels. For example, it is simple to tell the difference
between 2 and 3 ppm but almost impossible to tell the difference
between 19 and 20 ppm.
The effectiveness of the coil denitrator has allowed us to reduce the
amount of water we change by two thirds with the attendant reduction
in the cost of water conditioners and stress to the fish. The ten
dollar investment is paying large dividends in both time and money
saved and in overall water quality improvements.
The basic coil denitrator is a long section of small diameter tubing
with a slow flow of oxygenated water containing ammonia, nitrites and
nitrates, i.e., normal aquarium water. Aerobic bacteria naturally
colonize the insides of the tubing and transform ammonia to nitrite
and nitrite to nitrate. This process uses up the dissolved oxygen in
the front section of the coil and produces anaerobic conditions in the
rest of the length. Anaerobic forms of bacteria grow in this area
and reduce the nitrates and nitrite to gaseous nitrogen.
The trick in the setup is to pick the correct tubing size and length
and proper water flow such that enough bacteria of the right type can
develop and have enough time to complete the denitrification cycle.
Safety and efficiency concerns direct the actual design of such a
system.
The coil is simple to make from readily available materials. A visit
to a hardware store or nursery that carries drip irrigation supplies
will provide you with the basics. Fifteen to twenty-five feet of the
thin-walled black, 1/4" PVC tubing used for drip irrigation is perfect
for this application. Simple connectors are available that allow you
to attach the tubing to a source of water. This will generally
produce too much water flow but an inexpensive 1-4 gallon per hour
(GPH) valve is also available that allows for fine adjustments of the
water flow.
For optimum operation, the water should be mechanically but NOT
biologically filtered before entering the coil. This prevents
water-born particles from clogging the small diameter features of the
coil while supplying the maximum amount of ammonia and nitrite to the
aerobic bacteria. Unfortunately, this is difficult to accomplish in
practice since any mechanical filter media will also become a
substrate for nitrifying bacteria. A good compromise is to use the
water return of a canister or trickle filter as the source of water.
This water is very clean yet has been proven to provide enough "food"
for the bacteria.
For safe operation, the outflow from the coil should be passed through
a biological filter of some kind. At some point during the startup
period of the denitrator, enough bacteria will be present to reduce
nitrate to nitrite but not enough to take it all the way to gaseous
nitrogen. It is also possible that after being established, something
may happen that would disrupt the denitrification cycle and nitrites
could again be generated. You do not want to return this nitrite
laden water directly to the aquarium.
APPLICATION
Two of our large 90 gallon freshwater aquariums are heavily planted
and well stocked with fish. Even with the lush plant growth, we had
to change significant amounts of water to maintain low levels of
nitrates. Prior to implementing the coil denitrators, we were
changing 50% of the water every two weeks. This was time consuming
and quite expensive due to the water conditioning and plant fertilizer
products that we use.
Both of these aquariums have trickle filters which allowed a very
simple coil denitrator system. A hole was punched in the vinyl water
return line to the aquarium with an inexpensive drip irrigation hole
punch designed for this purpose. The water return line passes over
the trickle filter sump at the point the hole was punched so if any
leakage occurs it will harmlessly drip into the filter. A 1/4" right
angle connector pushed into the hole connects one end of the coil to
the return line. The back pressure from the 4 foot head is sufficient
to provide more than enough flow through the coil.
The small 1-4 GPH valve is put at the outlet end of the coil. The
valve clogs easily so it is best to put it on the outlet side of the
coil for easy periodic cleaning. A short piece of 1/4" tube is
attached to the other side of the valve and fits into a small hole
drilled in the filter drip tray cover. The water from the coil thus
passes back through the trickle filter providing insurance against
toxic nitrites. The coil outlet is a loose fit in the cover so it can
be easily removed for cleaning and monitoring water flow and nitrate
concentration.
The coil itself rests on the PVC plumbing coming from the filter pump.
It is not fastened down so it can be easily moved if access to the
plumbing is required.
Once set up, the water flow through the coil can be measured by timing
how long it takes to fill a container of known size. For example, if
it takes 6 minutes to fill a 500 ml container, the water flow is 5
liters per hour. Water flow should be checked regularly since
bacteria and their waste products will build up and restrict the coil
and valve. The valve can easily be removed and cleared by blowing
through it but the coil should be left undisturbed. We have found
that the flow through the coil itself is usually not impeded enough to
affect the operation and any attempts to clear the tube will probably
result in a disruption of the denitrification cycle.
The system takes 4-6 weeks for the aerobic and anaerobic bacteria to
completely populate the coil. Prior to this point you may find some
nitrite being formed if you have a sensitive test kit.
Once the coil denitrator is established, the nitrate reduction will
depend on the flow through the coil and what percentage of the coil
contains anaerobic bacteria.
RESULTS
In our set up, we use 15 feet of 3/16" ID tubing and have a water flow
of 3 liters per hour through the coil. The most recent nitrate test
with a Lamotte low range nitrate test kit showed 1.0 ppm
nitrogen-nitrate (4.4 ppm nitrate) on the input and 0.75 ppm (3.3 ppm)
on the output. With a reduction of 1 ppm (1 mg/l) and a flow of 3
l/h, the denitrator is removing 3 mg of nitrate per hour. This is
keeping up with nitrate production since the overall nitrate levels in
the aquariums are staying at around 4-6 ppm. There is no nitrite
coming from the coil as verified by a Lamotte nitrite test kit.
Note that the effects of the denitrator can only be seen if the
nitrate concentration of the inlet water is very low since the
resolution of test kits available to the hobbyist varies with the
nitrate levels. For example, it is simple to tell the difference
between 2 and 3 ppm but almost impossible to tell the difference
between 19 and 20 ppm.
The effectiveness of the coil denitrator has allowed us to reduce the
amount of water we change by two thirds with the attendant reduction
in the cost of water conditioners and stress to the fish. The ten
dollar investment is paying large dividends in both time and money
saved and in overall water quality improvements.
So where does this gaseous nitrogen go in your denitator? Also i have heard that sometimes these denitrators give off a rotten egg smell. Why is this? These are really easy to make with directions all over the internet and getting rid of nitrates in our aquariums would be fantastic. So why is it that very few people use these. There has to be more to it than i know.
Here's a reference that I believe answers your questions.
http://www.arofanatics.com/forums/showthread.php?t=137818
http://www.arofanatics.com/forums/showthread.php?t=137818
It looks like in that thread you posted they came to the conclusion that the gas a denitrator emits is N20. But i have been using n20 for years in cars and it does not smell like rotten eggs. So that is still unclear to me. ----------I have came up with my own conclusion here that the reason most people do not use a denitrator, even thou they can be made for cheap and work great is that it is just easier to do a water change.
Keep a log of the nitrAtes (along with ammo/nitrItes) before & during to let us now how long it takes to start working and how well.
Dr Joe
.
Dr Joe
.
I don't get it...
They say to use non-bio filtered water, yet suggest using the return line from a canister....which is a bio-filter, yes? Or should one have a spare canister with no media, just to run the de-nitrator?? I have a well planted, well stocked tank and am currently having nitrate issues. As has been said already, water changes sound alot easier...and cheaper.
One could also try feeding less...
They say to use non-bio filtered water, yet suggest using the return line from a canister....which is a bio-filter, yes? Or should one have a spare canister with no media, just to run the de-nitrator?? I have a well planted, well stocked tank and am currently having nitrate issues. As has been said already, water changes sound alot easier...and cheaper.
One could also try feeding less...
Canister filters use a multi-pass method of filtration (in other words they filter out a little a whole bunch of times, hence high turnover rates) so you still have food for the denitrAter.
If one were to use a larger diameter tubing, lets say the size of tubing you get with a python, and pack it with some sort of biological media, lets say Seachem matrix, would it improve the effectiveness of the unit? The matrix in the piping would help deoxyegenate the water quicker than just normal tubing, meaning a larger flow could be put through the unit and into the anaerobic center chamber.
