DIY Coil Denitrifier

[Duke]

I went ahead and decided to build this thing to combat high nitrates in my system without having to use bio pellets or carbon dosing. Hopefully this results in less water changes and better water parameters. The idea behind a the setup is you flow water through a very long tube and by the end of the tube the water has 0 oxygen left because the aerobic bacteria growing in the tube(coil) removes it all. Next the water that has been stripped of oxygen flows back through a chamber where anaerobic bacteria(which thrive in a no oxygen environment) strip the water of nitrates and convert it to nitrogen gas. so basically the water that leaves the reactor has 0 nitrates. its as simple as that. This setup is gravity fed from my tank and returned into my sump.

I started out with

2' length of 4" PVC pipe
2 4" PVC end caps
75 FT 1/4 OD .170 ID black plastic tubing
2 threaded 1/8 to 1/4" quick connects
3 90 degree 1/4" quick connects
12 dish scrubbers from the dollar store
1 1/4" ball valve quick connect

theres some other stuff i needed like glue and some tools.

I started out by coiling 65' of the tubing around the outside of the pipe to get it to kinda mold itself to that shape and let it sit for a while.

Next i moved the coil to the inside of the PVC pipe

With that finished i set it aside and drilled and tapped 2 holes in 1 end cap to match my fittings (1/8 fine thread), this will be the lid.

Using Teflon tape i installed the 2 quick connect fittings into the lid.

I then went ahead and cemented the bottom cap onto the tube.

i added a 90 degree fitting at the bottom just to get the water to exit the tube more in the middle.

Next i filled the chamber with 11 dish scrubbers from the dollar store( this is where the anaerobic bacteria will live)

Then i glued the top end of the tubing into the fitting on the lid( i used 1/8" fittings because the tubing fits nice and snug into the hole.. glue wasn't needed but since this thing is sealed i glued it anyways.)

So all that was left to finish it was to cement the lid in it and add the feed and return lines. and the finished product ready to run.

So just to recap, Water is siphoned out of my display tank into the reactor where it travels down 65' of tubing and during that travel aerobic bacteria living in the tubing strip the water of oxygen before it exits into the bottom of the reactor where gravity then flows it through the chamber of dish scrubbers that are covered in anaerobic bacteria that strip the water of nitrates back up to the top of the reactor and out into my sump.

To start off I'm using a valve to restrict the flow to 2 drips per second.. this will give the reactor time to start growing the bacterias needed for this setup to work, it should take a few weeks to a month to start seeing results and at that time i will gradually increase the flow as high as i can and still get 0 nitrate water out of the reactor. Ill update this thread with weekly water tests of both the reactor run off and of my tank water to keep record of my results. Any questions I'd be glad to answer. Thanks for checkin this out.

 

[Zakk]

So it's glued solid?  What if there's an obstuction or it needs an adjustment? 

I've never heard of anything like this, maybe you'll have the next marketable super product

 

[Duke]

its glued solid.. theres no opening it up at all.. any oxygen inside the reactor will kill the anaerobic bacteria. the only adjustment is flow and im using a simple ball valve to restrict the return. i should have mentioned that my 1/4 inch feed line from the tank has an airstone attached acting as a filter to keep stuff out of the reactor. Ill post pictures tomorrow of it running just my lights are off right now so cant get a good picture. i cant take credit for it.. it works on the same principles as a DSB.. in the deep part the is no oxygen.. and thats where the anaerobic bacteria live and convert nitrate to nitrogen gases..

 

[pulpfiction1]

actually they have been around for years,and some have had very good results,hopfully the gravity feed will work for you,keep up the good work and let us know the results

 

[crazybizzle]

pretty cool, good write up cant wait to see if it works

 

[Krazykarl]

Is this the same idea as a fluidized bed filter? I've been toying with the idea of making one to help with nitrates. Curious to see if this works or not. You might be onto something

 

[Duke]

Not 100% familiar with fluidiized reactors butc its basically 2 main parts, the coil which strips the water of o2 and the reactor itself which is an o2 free zone where the denitrifying bacteria can thrive.

 

[Blob-79]

Ya theyre not really like a fluidized bed at all. Coil denitrators have been in use for awhile.

 

[Duke]

So far so good, after a week running the reactor effluent is testing 10ppm nitratea and my display is at 20.. Skipped this weeks water change to see if There's any reduction happening yet. Will update again next week

 

[Blob-79]

hm, thats faster results then i was expecting. Looks like its well on its way

 

[El concistador]

pretty interesting.

 

[phi delt reefer]

glad to see it working well so soon.

 

[Darryl_V]

Im in disbelief.....tried this idea years ago and got no where.  Unless you feed these things with vodka, they work very poorly....at least this was my experience and read the same through my research.  With all the advances in carbon dosing I figured this idea has gone to the way side but you know I will never say you cant do something in this hobby because someone will come a long and prove you wrong.  keep us updated.

You know this is like those aquapure filters minus the vodka.

 

[Duke]

Im in disbelief.....tried this idea years ago and got no where.  Unless you feed these things with vodka, they work very poorly....at least this was my experience and read the same through my research.  With all the advances in carbon dosing I figured this idea has gone to the way side but you know I will never say you cant do something in this hobby because someone will come a long and prove you wrong.  keep us updated.

You know this is like those aquapure filters minus the vodka.

I'm with u still, im quite doubtful still myself, in theory its obviiusly going to do what its made to do but can it make a difference? Not sure yet,  just because it drips out low nitrate water doesn't mean much,  I need it to process like 20gpd at least to make it worth while. Then the whole reliability thing is still there... If it clogs There's no uncloggjng it.. So I would be shit outta luck and without a main source of bacteria to process nitrates it could be a recipe for disaster.  Time will tell I guess. And I have been dosing up until I started this up with poor results.. So if this fails ill be moving to bio pellets.

 

[Darryl_V]

If you do try biopellets be very careful adding them id you have high N and P.

 

[Zakk]

If you do try biopellets be very careful adding them id you have high N and P.

Agreed, but once a pellet system is up and running, it's great.  I've noticed the pellets last for AGES too, which was a nice surprise, I thought it would be another monthly bill...

 

[Duke]

well after another week or so.. water tests are still promising.. lower nitrates.. but high nitrites coming from the reactor. apparently this is normal in starting up a denitrifier as the bacteria builds itself up..

 

[Blob-79]

hm, thats interesting.. that would mean things are dieing in the coil? You say this is common just on startup of the coil, or is it ongoing?

 

[Duke]

just during the cycling of the coil, im not totally sure on what the theory is behind whats going on.. so ill just copy and paste a quote from someone who sounds like they know what there tlaking about.. lol

As tank water is pumped into the reactor, it is laden with all the chemicals inherent within the system including nitrates. Also present is oxygen,(referred to as O-2). Anerobic bacteria cannot survive with even the smallest traces of O-2 and to eliminate this gas from our reactor we have provided all that surface area within the coils for these O-2 munching helpers. As the water works is way down and around the coils, the aerobics strip the water of all O-2 as they convert ammonias into nitrites. The nitrites then enter the center chamber and flow back out into the aquarium. This is why you will test positive for trace nitrites when checking the effluent going back into your tank. In fact, you may experience a higher concentration of nitrites than you have since 1st cycling your system way back when. Don’t be alarmed…this condition is perfectly normal and part of the cycling process of your denitrator.

Slowly, as more and more aerobics inhabit the coils the amounts of available O-2 in the lower portions of the coils will become smaller and smaller. Eventually, all the bacteria in the upper reaches will have depleted the O-2 by the time the water enters the center chamber.

O-2 depleted water now occupies the center section of your chamber. The bio media provides the area for the denitrifying bacteria to gain a foothold and begin to flourish. The amount of nitrate concentrations will ultimately determine the size of this colony once fully established. The colony will expand and contract as the available nitrates fluctuate.

 

[Fraggle Rock]

You still using this Duke? And if so hows it working for you?