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Hey I was reading about coil denitrators I was wondering if anyone has made one and what was there experience. I was thinking of making one for my freshwater tank.

I figure I can make one for about $20 maybe put it on a test tank before my main.


My LFS has some commercial ones and they tell me on their lightly stocked salt-water tank it never gets above 5 and that's with just water top ups.

Tried and failed. They sound good in theory, but I've never actually talked to someone whose DIY worked to any degree. Heck, if it did, everyone would make one!

I say go ahead and try if you want. You don't have much to lose except your 20 bucks. Plus, if you find a good, cheap way to do it, you can patent it and sell it.

I built a DIY Cannister denitrator. It's similar to the coil version, but it is actually designed for FW use, as there are some major differences.

Standard coil denitrators won't work on FW tanks for two reasons: denitrifying bacteria is essentially non-existent in the freshwater aquarium, and freshwater denitrifying bacteria feed off of carbon, which coil denitrators lack.

They work in essentially the same way, but there are a few differences. I didn't use the coil design, I just have it flowing straight through. My design is essentially a reverse-cannister filter that does about 1 drop per hour.

After you build the thing, you'll need to get a colony of bacteria. You can obtain such a colony from a local body of water (preferably a slow moving stream or a pond). These bacteria thrive in essentially dead spots full of rotting crap, so grab a handful of mud/leaves/crap and put it in a bucket of water from the source. Bring it home, put some of your media (bioballs and ceramic rings work well) in the bucket with the crap, and over the course of a few weeks, slowly remove the original water and replace it with old tank water (nitrate source). After about a month your media should be colonized, and you can take it out of the bucket and put it into your denitrator.

Do remember that this bacteria feeds on carbon! The decaying matter/dirt/crap provided the carbon source in the pond and the bucket, but now you have to provide it. You can put some old carbon from your tank into the denitrator to feed them. Spread it all around on top of the media.

Here's some pictures of my little setup.

http://i2.photobucket.com/albums/y22/PoisonWaffle/DSC01112Large.jpg
http://i2.photobucket.com/albums/y22/PoisonWaffle/DSC01111Large.jpg

If you have any other questions about it, let me know and I'll see what I can do. One of my friends built one for his reef tank, so I could ask him for ya

Interesting pictures poisonwaffle I assume the clear pipes are in and out but what is the black one? 1 drop an hour seems slow given that an average drop is 20 to a ml it would take years for the average tank. Most of the commercial ones seem to run at a steady drop. How much nitrate reduction do you get? I have looked at a commercial one (http://aquaripure.com/index.htm) that seems to use basic principles (ie not a sulphur one) and the use sugar water or alcohol to feed it weekly which provides a carbon source does throwing in activated charcoal work ok.

I have experimented using the outflow on my canister to feed the water through the pipe and it works fine. I have just an outlet not a spray bar so it pumps pretty fast and the outlet is about 20mm diameter so 6mm pipe doesn't restrict it much.

I figure i will try a few things to see maybe coil and another design, especially as i went to the hardware and picked up 45' lengths of drip system hose for$1.50.

It's in a 29 gal tank, btw. I never exactly measured the output precisely, but it isn't much at all. I hadn't checked on the thing in a few years, so I just checked on it today. If I hold the output above the surface of the water, it will drip, and there's about 5 mins before the next drop comes out. And I suppose there's more head pressure when the hose is higher, so I'd venture to say about a drop every 4-5 mins? At any rate, the flow is VERY very slow...

The clear tubes are vinyl tubing, yes, in and out. The black one is the power cord for the pump. To get the pump in there, I had to cut the cord, string it through the hole I drilled in the lid, and splice the cord back together o.O

What would be the advantage of having this? Unless your tap water has high nitrates?

It keeps your nitrates down... usually WAY down! Less nitrates = less waterchanges!

Of course, it's still a good idea to do waterchanges to keep everything else in balance (tannins, pH, mineral levels, other misc nutrients, etc), but if your system is balanced enough (for example, I have rocks with a high nutrient content in them... they fertilize the water as they break down), theoretically you can go without waterchanges...

It could be useful for those in drought conditions that can't do water changes but there are alot of issues with encouraging the bacteria that use nitrates. Which is why you keep everything oxygenated and stirred in a normal tank setup. The main problems with denitrators that I've been told is first the bacteria survive in areas without oxygen so the water going through the denitrator has to have all the oxygen used up and that means the water coming out has no oxygen. Usually bad for a tank. Another problem is other gases are relased from these bacteria and some of them toxic. That's the gas bubbles that come up and the bad smell. This is going into your tank. It may be nitrate free water but I'm not sure I'd call it clean water. Might not actually be a good idea to build a denitrator that runs more water through faster.

I had much better success and fewer problems adding lots of porous rock to my tanks. Rock is often used as a main source of filtration and denitrification in marine tanks. It also works great in brackish tanks. I finished fishless cycling my brackish tank with over 80ppm nitrates. Added the rock and waited around a week or 2 before I got back to doing a water change and moving the fish over. Well when I tested my nitrates they were at 40ppm and I was still adding fish food daily. No plants, only porous limestone. Despite having to heavily overfeed the bumblebee gobies that tank never has had any nitrate issues with minimal water changes. It also has somewhere between 30-40lbs of rock for a 30g tank. I've seen some of the same success in my new freshwater 40g although not quite as remarkable but for every few pounds of rock I add it seems to gain 2-3ppm of nitrates less every 2weeks. However in softwater tanks limestone and coral rock is not a possibility. A few have said driftwood might provide some of the same denitrification but despite packing a couple tanks full of driftwood I never saw a noticeable effect.

Also worth noting though that marine tanks tend to have alot of aeration and still have issues with low oxygen. It's not uncommon to have multiple large powerheads blasting the water around the tank and some even have tidal systems which cause waves throughout the tank on a timer. A well setup marine tank should have zero nitrates at all times but I would think all the biological processes going on to filter the tank using live rock and sand is part of the cause of such low oxygen levels.

Hi,
First, I know of no rock that contains the nutrients
necessary for a successful tank. The only rocks that
directly affect a tank are classed as Carbonates, and
consist of rocks such as dolomite, limestone, and others.

Carbonates, over time, leech into the water and have the
effect of increasing the pH (into the 8's) and increasing
the General Hardness (GH).

The only thing that "porous" limestone or any other
porous rock does, is increase the surface area on
which more bacteria can grow on. This drastically
increases the colonies' size and their ability to
cleanse the water.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Areas deep inside porous rocks create anearobic conditions and allow denitrying bacteria to exist. It's a well known benefit of rock in marine tanks. Not only the organisms living in the rock break things down but the rock itself allows for denitrifying bacteria to establish. Any porous material can develop such conditions if the flow of water isn't great enough. In a rock stack you get a few stagnant areas where the flow is blocked even when dealing with a marine tank and numerous powerheads. Pourous rocks do allow for some denitrification but the effectiveness seems to go down greatly between marine conditions to freshwater. It's still noticeable in freshwater if you have a tank with enough rock. I do mean alot of porous rock not just 1 or 2 decorative rocks. Around 1lb per gal

along the lines of what sham was saying,Any one used sera siporax or seachem matrix the manufacturers state they provide anerobic conditions that assist with the breakdown of nitrate.

The rocks I have in my tank are iron rich sedimentary (essentially compressed soil) rocks from the Badlands area of western South Dakota. They're about as soft and porous as limestone, but they're reddish. I don't imagine that they can keep up with the plants' demand for nutrients entirely, but they probably help some. Either way, a large volume of plant matter in my tank gets eaten and pooped out on a daily basis, thus recycling the nutrients back into the water column and substrate.