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This web site contains information about Pet Fish Talk, the weekly internet talk show about keeping pet fish in aquariums, fish bowls, and ponds.
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a Pet Fish Talk Show now.
An MP3 PodCast titled "Detritrification" on
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Pet Fish Talk about keeping pet fish in aquariums, fish bowls, and ponds.
"Denitrification - How to Remove Nitrates from Aquarium Water - An MP3-Podcast on      
Pet Fish Talk about keeping pet fish in aquariums, fish bowls, and ponds. Pet Fish Talk about keeping pet fish in aquariums, fish bowls, and ponds.
In this Special Pet Fish Talk Show first Tom and Robert in New Jersey talk about denitrification, then Tom and Nevin talk about denitrification of aquarium water.
Click here now to hear the Special Pet Fish Talk titled "Denitrification", which is about 92-minutes long.
Aquarium water denitrifier
Shown above is the first denitrifier that Nevin built and talks about during this special show. This denitrifier takes in water at the upper left. The water flows down the 4" diameter ABS pipe, makes a U-turn at the bottom, and comes back up, then flows back into the system. Inside the pipe is denitrifying media, which in this case at this time is bio-barrels.
As the water passes through this denitrifier, the bacteria first consume all the oxygen, then the bacteria must rely on nitrate, which they consume and denitrify the water, then the water flows back into the system. This denitrifier has never removed much nitrate from the water. Probably because the media does not contain enough surface area for the bacteria.
Aquarium water denitrifier
Shown above is the second denitrifier that Nevin built. It is an inexpensive 5-gallon plastic utility bucket that is filled with media that is sold and labeled for denitrification. The water flows from above into a 2" diameter piece of plastic pipe that carries the water to the bottom of the bucket. The water then flows outwards and upwards until it overflows the bucket.
This simple denitrifier has reduced the nitrates in this system from over 80 ppm to about 40 ppm, which is thought to be about ideal in a system like this. So this very simple denitrifier works very well.
Aquarium water denitrifier
Here's Nevin pointing to the third denitrifier that he built. This denitrifier is again contained in a 5-gallon plastic utility bucket. The water is pumped from the system into the bottom of the bucket and flows upwards through the denitrifying media. Near the top of the bucket is a threaded plastic L-fitting that screws into the bucket and connects to a piece of clear plastic tubing that returns the water to the system.
This denitrifier is now working too well and removing all the nitrates, which may force some bacteria to use sulfates and produce hydrogen sulfide. When Tom inspected the system, he noticed a smell that may be hydrogen sulfide. The solution may be to remove some of the denitrifying media in the bucket. Incidentally, on the left in this photo is a commercial bio-wheel filter, which converts ammonia and nitrite to nitrate.
Click here for more about using Lava Rocks for the Denitrification of water in aquariums and fish bowls.
An Email from Jose from Maryland about
Using Lava Rock to Remove Nitrates 
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 about 80ppm. 
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
Reply: Hi 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 and are already seeded with the denitrifying bacteria. Click here to 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 test 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 immediately. Click 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.
An Email from Bill about
Using Lava Rock to Remove Nitrates 
Hello, 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 nitrates.
Thanks for you help
Bill V.
Reply: Hi 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 here for 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 sulfide.
Remember, keeping nitrates between 20 and 40 ppm is very important to almost all freshwater fish.
I hope this information helps you and your fish.
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Pet Fish Talk about keeping pet fish in aquariums, fish bowls, and ponds.
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