Guide to DIY De-nitrator

I have noticed that some bros still have many queries about how to go about doing a diy de-nitrator therefore I decided to post this little "article" I have written. It compiles all information in all my previous related thread and also all questions through PM or in the forum that I was answering to. Hope this could help bros who might be interested to know some basic procedures in diy-ing their very own de-nitrator. This "article" serves only as a general guide to help those who need it. It’s not to assume that I’m totally correct as this article only sort of consolidate some things I have learnt from very experienced bros here, through my readings and personal experiences. This article is also not debating on the best method to remove nitrate. Of course there are many other mechanical and chemical or even natural ways, which are sweared by some bros here who has experience using them. This article is more for bro who has done some researched and decided to diy their own coil de-nitrator, to help them to accomplish in their forthcoming diy project. I have included whatever that I know in this post so those new bros don’t have to search through the whole list of old threads jus to gets bits and pieces of loose info. This is going to be a long read but I think it will definitely benefit many. I have included the general guide, the science behind cycling and some extra info, which you might be interested if you are building one yourself.

The Science behind the cycling process: "Nitrogen Cycle"

If you are reading this article, congratulations! It means that you already understood what the entire nitrogen process is about. That’s why you are finding ways to remove the toxic nitrate if accumulated in high level without water change. Ammonia (toxic) will need to be broken down to nitrite (toxic), which needs to be broken down further into nitrate (ok level of toxic for fish). I can safely and proudly assume that bros here already have tip top water management in terms of zero NH3/4 and NO2. Give yourself a pat on your shoulder. Now we are all looking for more advance stage of water management. That is how to further break down NO3 (nitrate), which is a by-product of NO2 breakdown process, into nitrogen gas and to be escaped through the tank water surface.

My diy is based on a few assumptions/facts:

1. Anaerobic bacteria can only be cultivated in oxygen free environment.
2. Oxygen riched water passing thru a 20m 1/4" tube at drip rate will emerged with oxygen free water. This is due to the aerobic bacteria along the inner tubing consume all the oxygen. By the way, its this aerobic bacteria commonly found in our filter media that break down your NH3/4 to NO2 to NO3. Hence we have accumulation of NO3, which will be toxic. They can be removed through water change. Some find it too expensive to do constant large amount of water change for their huge tanks. Even our tap water has certain amount of NO3. Therefore we are looking for method to cultivate the anaerobic bacteria to tackle the high NO3 problem. Thus reducing the need of large constant water change.
3. Anaerobic bacteria hosted on the bioballs will convert the nitrate to nitrogen.

Material require to build the coil de-nitrator

$3 for 25m air tube, $8 for 2.5ft 4" pipe, $6 for 2 4" end caps, $1 for air tube connectors and valve, $2 for super pvc glue. 100+ bioballs from ios tank. Input pump is tapped on to the air hose of 1400l/h powerhead in the main tank meant for water current (tat means I dun need extra powerhead to drive the de-nitrator and incur more electric bill). Silver spray paint left over from my previous tank cabinet work project.

Steps on building it

1. It’s not easy to coil the air tube neatly by the side of the inner pvc pipe. So I just coil it round my hand. Make sure no acute bend and slowly push the bundles into the pvc pipe. Having done that. I’ll have one end of the air tube at the bottom of the pvc pipe and the other end extend up to the top of the pvc pipe.
2. I’ll use the suction cup that is used to hold the tank partition and stick it on one of the end cap. Then I’ll position the end of the air tube at the bottom of the pvc pipe onto the partition holder. This is make sure that the water outlet from the air tube will be positioned at the center of the bottom pvc pipe.
3. Cover up the end cap at the bottom of the pvc pipe. Seal up the end cap with the pvc glue.
4. Temporary cover the top end cap. Wrap the top end cap with newspaper and masking tape. Spray paint the entire pvc pipe including the bottom sealed end cap.
5. Drilled 2 small holes on the top end cap sufficient to tightly squeeze through the 2 air tube connectors.
6. Insert the 2 air tube connectors into the holes and seal them up with pvc glue.
7. Connect the top end of the coiled air tube in the pvc pipe to one of the connector at the top end cap.
8. Fill up the pvc pipe with bioballs.
9. Top up the de-nitrator with tank water.
10. Cover the top end cap and seal with pvc glue.
11. Remove or break the air inlet connector of the submersible powerhead and insert a segment of a new air tube into it. This is to pump the water from the tank into the de-nitrator. The air tube needs to be inserted through the air inlet of the powerhead and position all the way towards to motor. In this case, while water is pump out fro the powerhead outlet, at the same time it will also be pushed though the air tube into the de-nitrator.
12. Switch on the powerhead. Water will flow through the coil air tube in the de-nitrator and flow out from the bottom of the pvc pipe. Water and pressure will build up in the de-nitrator. The other free end of the air tube connector at the top end cap will automatically push the water out by pressure.
13. Connect an air tube to the outlet of the de-nitrator and the other end of the air tube connects to an air valve. This is use to control the water flow rate later on.
14. Now your de-nitrator is working. Congratulation! However that’s only the mechanical portion.
15. In order to kick-start the anaerobic bacteria, we need to feed the bacteria in the de-nitrator with sugar. Cut the inlet air tube between the powerhead and the de-nitrator inlet valve. Put in some fine sugar in the air tube. Connect back the air tube with a connector for future feeding if necessary.
16. Adjust the air valve at the outlet air tube and let the water flow at a rate of one drop per second.
17. We are done here!

Pictures and links

http://www.arofanatics.com/forums/sh...2&page=1&pp=10

http://www.arofanatics.com/forums/s...ight=denitrator

Frequently Ask Questions

Q1. Saw your denitrator. Really impressed by it. BTW how does water flow thru the whole system? From what I could gather, the powerhead pumps water into the long coil of hoses & ends up at the bottom of the denitrator. Water then exits & flows upwards thru the bioballs & comes out thru the outlet valve. Is that about right? What do you use to pump water thru the system?

I was hoping to build one. Would you mind, if it's convenient for me to pay you a visit to see your denitrator? Thanks for your time. Cheers.

A1. Thanks for your compliment. You are right on how does the water flow through my whole system... with the help of a powerhead. I've a powerhead in the main tank for water movement. At the same time I've detached the air hose inlet of the powerhead for a hole to insert my de-nitrator water inlet tube. In this case I only use a single powerhead for 2 different purposes.

You are most welcome to visit. However its all sealed up and there is really nothing to see. You've already got the whole idea correct and maybe I can help to elaborate more on the forum to benefits more bros. Please do let me know if you've more clarifications. I'll try my best to answer. Thanks.

Q2. Thanks for the explanation. The PVC tube has 2 end caps. 1 end cap at the bottom is sealed with no outlet. The other on top has to outlets. 1 outlet is the inflow from the tank & I presume the coiled hose inside the pipe is connected to it. The other is the outflow from the pipe. Now how does the water flow out? There is no hose attached the the bottom of the outflow valve right? Does water flow out just from the pressure built up inside the pipe?

Do you by any chance have pics of the assembly of the denitrator? Thanks again.

A2. You hit the right note again. The water flow out from the built up pressure inside the pipe.

Sorry that I did not take enough pictures during the building process to provide sufficient aid. Hope the link to one of our AF bro here will help
http://www.arofanatics.com/members/...ileddenitrator/

Also I've added a diagram and some write-up in the forum. Hope that will help too.

A summary and some assurance here....
1. coil the tubing in the pvc pipe
2. one end expose at the inner bottom, the other end at the innner top
3. use a tank partition sunction cup to position the bottom tubing opening at the centre of the bottom end cap
4. cover and glue up the bottom end cap with pvc glue
5. fill up pvc pipe with as many bioballs
6. fill up pvc pipe with tank water almost to the rim
7. fix the upper tubing to the valve at the bottom of the top end cap
8. cover the top end cap and glue
9. run the powerhead with the tubing connected to the inlet valve of the top end cap
10. water in the pvc pipe will raise n pressure built up
11. water will be streaming out from the outlet valve from the top end cap
12. a tubing connected with a control valve should be connected at the other end of the outlet tubing to control the flow rate

That's it! You'll be amazed how easy it is. Having built your de-nitrator, then we'll take about the flowrate, feeding food into the de-nitrator, etc.. Can check back to the link to my diy de-nitrator thread discussion. Let me know anywhere you are still not sure of. I think you are already there and all set to start building it.

"Water change is a history" .... wah so nice .

Q3. Where did you get the valve connector from? Do you need to drill into the end cap to attach the valve connector? What do you use to attach the connector to the end caps? Thanks again.

A3. The L-shape tubing connector can get from any lfs. I got mine from aquastar y934. Yes I drilled 2 small holes through the top end cap to insert the connectors. It is much neater and also prevent cracking of the end cap.

Another important part to success. The glue used to seal up the end caps as well the connectors to the top end cap. Its a pvc glue. Very powerful and quick dry in few minutes. It comes in a small round steel container. Its cap is attached with a brush to apply the glue. It has only Japanese wordings on it. I got it from the hardware shop which I bought the pvc pipe and end caps. Just tell them that you want the glue to seal the end cap and pvc pipe they will know what is it.

Hope its clearer this time. Please let me know if you have any further clarification.

Q4. Sorry. I got a few more questions.

1. The inlet connector has to have two tapered ends, so that the air tubes can be connected to both ends, right? Where do you get such a connect?

2. How in the world did you manage to coil the tube on the inside of the PVC pipe so neatly? Care to share the trick to it?

3. The hose to the inlet goes into the air intake of the powerhead. What does that do? Does it pump water out or suck water in? I always thot the air tube on the power head suck as air in to be pumped out by the powerhead.

Thanks again for your time & patience.

A4. Not at all. I'm sure everyday you handle much more aro illness questions then we are now.

1. Actually not necessary to have a special L-shape tapered tubing connector. the idea here is to use a solid connector so that it could be held strongly in the end cap hole. As I mentioned I got everything from aquastar Yishun blk 934 lfs. Except the pvc pipes and end caps I got them from hardware shop.

2. Very good question here. Guess having clarify all these will save you a lot of time and frustration when building it. The idea here is for the water to pass thru the long tubing and surface from the bottom of de-nitrator through the bioballs to the top and flow back to the tank. It does not matter whether to coil it neatly and nicely by the inner side of the pvc pipe. Having said that, I just bundled the tubing neatly around my hand (make sure no severe bending angle) and slowly put into the pvc pipe. You also noticed that I use a almost 3 ft tall pipe. Now you know my reason. Can you imagine in the pvc pipe, the bottom squeeze all the tubing and the top half occupied by all the bioballs.

3. Aha. Thats normally how the powerhead air hose works. Now over here there is a slight modification to the powerhead air inlet. Some powerhead allows you to remove the air inlet connector. Having done that. I squeeze the de-nitrator tubing inlet through the powerhead air inlet hole, all the way into the powerhead towards the motor direction. In this case, water is forced out at the powerhead outlet and at the same time will forced through the tubing into your de-nitrator. Wonderful and amazing isn't it.

Once again please don't mention. Its really nothing compare to your effort in the forum.

Q5. Any particular brand of powerhead that allows you to make such a modification? Thanks again. You been a great help. Cheers.

A5. You hit the right question again. I'm using Resun SP-2500. The air inlet connector can be removed by hand. Please check again before purchase. If you have an existing powerhead and the air inlet connector is fixed. You can just break it and slowly use a power drill to drill a small hole, barely enough to squeeze the tubing in will do.

Almost there now. Good luck bro.

Q6. I've built it, but realised that I can't get the powerhead to pump water thru the pipe. What I've done is to reverse the flow of water. By connecting the outlet directly to the air hose portion, it sucks water out of the pipe which in turn would suck water out of the tank thru a hose connected to the inlet. I find it makes more efficient use of the power of the powerhead this way.

I just have to seal it up & test it. What is this about feeding the bacteria with suger solution? How long before it starts to work? What is the flow rate thru the denitrator? Thanks again.

A6. Sorry for the late reply. Well done! I've built it. De-nitrator needs to be tuned to a flow rate of 1 drop of water per seconds. Too fast will not deplete the oxygen in the water flowing thru it. If you do it the reverse way, you may need to think of a way on how to make the flow rate at 1 drip per sec.

You need to feed a very small pinch of fine sugar into the de-nitrator. This is to kick start the colonization of the anearabic bacteria. Totally shut off the water flow into the de-nitrator for 1 week. After that starts at a flow rate of 1 drip per sec. Initially the first few hours you'll sense a pangent smell. Thats nitrogen sulphide and its normal. After the smell shall be gone and you can start measuring the water from the de-nitrator output. After about a month time, you'll find zero nitrate from the output of your diy-ed de-nitrator.

Q7. Hi...! I've seen yr wk in the forum. V nice piece. Would u mind teaching me how to construct..? I've some doubts after reading the materials. http://saltaquarium.about.com/od/pr...ycoildenitr.htm


M i rite to say i end of the tubbing paste to the end cap at the bottom and the other end connect at the top connected to tube connector..? Water will flow from the top tube connector is it..? wat to do wif the other tube connector and valve..? las k use other media to replace the bio balls..?

A7. thks for your compliement. yes u r rite about the tubing. water is pump in fro the top tube connector all the way to the bottom. the other outlet tube connector n valve will control the flow rate. of course u can use other media. bioball is just a media with large surface area.