Coil Denitrator

[rsman]

generally if the coil is long enough then you dont have to feed it, but at the same time, if the water isnt moving thru the unit fast enough itll create hydrogen sulfate gas, if its moving too fast itll create nitrite.

output into the skimmer is a good idea output into a refugium is a better one.

 

[bbragg]

The coil, I believe, is where the aerobic bacteria colonize and remove the oxygen and use ammonia and nitrites in the water as food. Beyond the coil, on some other substrate or medium is where the anaerobes do their business of cracking the nitrates into N2 gas. I beleive they require a carbon source and a low pH for the best efficiency. In fact, I've seen a study concerning wastewater nitrate removal that suggests a pH between 6.5 and 7.0 is optimal. I was therefore considering feeding the thing from my Calcium reactor as the pH of the effluent is about 6.7 and I'm running a drip rate of about 14ml/min.

 

[rsman]

The coil, I believe, is where the aerobic bacteria colonize and remove the oxygen and use ammonia and nitrites in the water as food.

that it is
Beyond the coil, on some other substrate or medium is where the anaerobes do their business of cracking the nitrates into N2 gas.

yep
I beleive they require a carbon source and a low pH for the best efficiency. In fact, I've seen a study concerning wastewater nitrate removal that suggests a pH between 6.5 and 7.0 is optimal.

the output water from the coil will (if it did its job) have a ph of below 7, when it removes oxygen it gives back co2, which is how it uses its carbon, and in doing so lowers the ph.

there is plenty of a carbon source in almost any fish tank to provide the bacteria.

I was therefore considering feeding the thing from my Calcium reactor as the pH of the effluent is about 6.7 and I'm running a drip rate of about 14ml/min.

be very very carefull here, the coils job is to consume alot of the oxygen, if it consumes too much hydrogen sulfate gas is released, to do its job it requires water with oxygen to be fead into it. without oxygen to react with the bacteria create hydrogen sulfate gas.

also look at the real need for efficiency in a fish tank you dont really need the unit to be super efficient, and it really wont help lower the nitrates any further

 

[Uncle-Edgar]

I might be jumping into the middle of something with both feet w/o truly understanding it, BUT, if 100 feet of black hose is good, wouldn't 200 be better. I've been quietly lurking in the shadows hoping to find reliable info confirming that the denitrators really work. I hadn't thought about smaller tubing, only, the bigger stuff.

If 200 is good what about 3. With the smaller tubing you could get a bunch in a reasonably small enclosure.

 

[rsman]

I might be jumping into the middle of something with both feet w/o truly understanding it, BUT, if 100 feet of black hose is good, wouldn't 200 be better. I've been quietly lurking in the shadows hoping to find reliable info confirming that the denitrators really work. I hadn't thought about smaller tubing, only, the bigger stuff.

If 200 is good what about 3. With the smaller tubing you could get a bunch in a reasonably small enclosure.

first off they do work. thats not really something to debate. does it work for fish tanks, thats up for debate, IME they wont remove all nitrate, but they will do a good job with alot of nitrate and for me thats good enough, ill allow my LR/DSB/plennum to handle it, or in my FO and breeding tanks ill live with the small remaining nitrate.

there are several problems with coil denitrifiers one being that the bacteria doesnt like being in high flow areas, another being that you want the coil to only remove ammonia/nitrite and alot of oxygen, the larger diameter tubing requires a longer coil, the smaller diameter tubing requires a shorter coil.

if your coil is too long then you have to go so fast the bacteria wont remove nitrate, or you will go so slow it will basically poision your tank.

if its too short its not effective at removing oxygen and you end up with a very slow nitrite source

instead of 200' you could run 2 100's though or 3 66's or 4 50's

the stiff vinyl tubing sold for ice makers at home depots in a 400' roll for $20 is nice stuff to use, and 75' works nicely, you can run many coils into a larger bio chamber and have a nice flow thru, IME it still wont lower nitrates below about 5ppm.


when i built the one on my breeding setup it cycled with only a few fish but was expected to handle much more than a few, its done its job well, but even with a few fish it still couldnt do less than 5ppm nitrates.

 

[Uncle-Edgar]

Finally, I think I'm getting the picture.

I wasn't trying to debate, just trying to figure out if taking the time to put one together is worth it. I'm thinking more and more that it's time to give it a try. Thanks again.

duane

 

[Spring1]

My son, who is quite handy with acrylic, recently built this coil denitrator for me. It is still cycling. We used a 7 1/2" acrylic cylinder 15" tall with 100 ft of airline tubing. The diy instructions we used said to place a few grains of sugar in the intake before turning on. I suppose this acts as the glucose solution mentioned by bbragg.

Spring

 

[rsman]

My son, who is quite handy with acrylic, recently built this coil denitrator for me. It is still cycling. We used a 7 1/2" acrylic cylinder 15" tall with 100 ft of airline tubing.

sweet looks awesome,

how much $$$ to build it ???
how much water are you able to move thru it ???
is the cylinder blue ish or is there something else to give it that color??

I built a few but they dont look anything close to that nice

The diy instructions we used said to place a few grains of sugar in the intake before turning on. I suppose this acts as the glucose solution mentioned by bbragg.

its not required, but ive seen it stated that a little at the beginning will help it to cycle, I havent tried it all mine are cycled already

 

[Spring1]

Thanks rsman, I was quite pleased with the results myself. The blue coloring is from the bio-balls in the center of the unit showing through the clear airline tubing. The cylinder was 20 bucks, I got it from Anchor Plastics here in Louisville. 10 bucks for the tubing, $15 for the bio-balls, and probably another $15 for fittings. The top and bottom are made from some black acrylic scraps. The whole thing probably comes in at under $65.00. Much cheaper than the 200 bucks for a store bought one. I'm using a Cap 1800 pump rated at just over 600 gph. It seemed to take forever for the thing to fill up. Is this normal? How do I know if I need a bigger pump on it?

Spring

 

[traveller7]

Spring 1,

To confirm proper rate of flow:

1. Get a great Nitrate and pH test kit
2. Test the output

If the output water still has measureable Nitrate levels, slow the flow down bit by bit until Nitrate measures "0"

If the output water measures "0" nitrate, then increase the flow slightly.

Dialing in the proper flow will likely take a few weeks during the initial install and cycling of the denitrator. It really helps to have a proper valve and bypass on the pump for this application.

Even after set up you should check denitrator output at least once a month for efficiency. Your specimens are growing, dying, your pump is clogging, slime is gunking up your denitrator tubing, etc.

Pay attention to the output smell, while I have not encounter the "rotten egg" sulfide conditions, apparently it can happen. It takes a very minute amount of hydrogen suflide to create a very big stink so you will definitely be able to "nasal detect" pior to damaging your tank.

Enjoy the new gadget.

 

[jrutler]

I built one of these several months ago. I've continuously battled the drip flow rate. I'm running it off of gravity from an overflow, and I should have a pretty consistent positive pressure into the coil. But the little airline valve I'm using on the output keeps getting clogged - I guess with salt creep.

Anyway, I haven't checked it in a while, but I was seeing a drop in nitrates at the output relative to the tank level.

Anyway, I had thought that if you were to build a HUGE coil, the water flow could be large enough that the output could be unrestricted. Just put a PH on it and let it go.

 

[rsman]

To confirm proper rate of flow:

1. Get a great Nitrate and pH test kit

you should be testing nitrate and nitrite, ive not heard of testing the output PH as a regular job???

2. Test the output

If the output water still has measureable Nitrate levels, slow the flow down bit by bit until Nitrate measures "0"

If the output water measures "0" nitrate, then increase the flow slightly.


if the unit is not cycled yet and nitrites are picked up slow it down alot, if it is cycled and you get nitrites slow it down just a tad.

 

[rsman]

I built one of these several months ago. I've continuously battled the drip flow rate. I'm running it off of gravity from an overflow, and I should have a pretty consistent positive pressure into the coil. But the little airline valve I'm using on the output keeps getting clogged - I guess with salt creep.


is the unit cycled yet ???

Anyway, I haven't checked it in a while, but I was seeing a drop in nitrates at the output relative to the tank level.


please do so we can help you get it working

Anyway, I had thought that if you were to build a HUGE coil, the water flow could be large enough that the output could be unrestricted. Just put a PH on it and let it go.

you didnt really give detales on what a "HUGE" coil was, are you talking length or diameter, or both ?? and yes once its cycled you can do almost unrestricted flow, depending on your source usually a powerhead with a bypass.

 

[jrutler]

rsman-

Thanks for the offer of help. I'll go over the filter tonight and do some testing to see where I'm at.

is the unit cycled yet ???

I think so, but I'm not sure. It kept plugging up w/ no flow, so I had to start the cycle over again.

you didnt really give detales on what a "HUGE" coil was

8' tall, 1500+ ft of somewhat larger diameter tubing (3/8" or so) for better flow.

I'll get back tonight on testing parameters. I had opened the valve to a steady trickle and submerged it to try and keep the flow going. Last I checked, the effluent seemed to be slightly less on nitrate than the tank water. The resolution of my test kit kept the results a little hazy.

 

[Spring1]

Yikes!:eek1: I turned on the denitrator yesterday, I set the drip rate at 66 drops per minute. Tested the output this morning...... No sulpher smell, nitrates of output @ 10ppm, nitrates in tank @ 30ppm. NITRITE of output is a whopping >5.0! Trites in tank have risen to .25 ppm. I've adjusted the output of denitrator down to 15 drops per minute. I'm really concerned about the TRITES rising in this 125g tank. What should I do now? How long does it take to cycle this thing? My tank was a fish only until recently when I added 440 watts of vho. I only have a few corals in it. Should I move them to another tank?

Spring

 

[rsman]

NITRITE of output is a whopping >5.0! Trites in tank have risen to .25 ppm. I've adjusted the output of denitrator down to 15 drops per minute.

good thats what you should have done.

I'm really concerned about the TRITES rising in this 125g tank. What should I do now?

test it tomorrow nitrite should fall in the tank FAST do expect the nitrates to rise though

How long does it take to cycle this thing? My tank was a fish only until recently when I added 440 watts of vho. I only have a few corals in it. Should I move them to another tank?

I would just leave them, the tanks nitrites wont cause to much more stress then the 30ppm nitrate. expect them to react and recover fairly quickly. like many things in this hobby the cycle time varries 4 ~ 6 weeks is generallly what ive read and experienced. if its gona take the 6 at 4 you should be seeing an improvement but not as much as possible.

 

[Spring1]

Thanks rsman, I just did a water change saturday, but I have water in the making as we speak. Do you recommend I do another change? Seems like the logical thing to do. Do you think the denitrator will make a dent in a tank this large?, or should I have left well enough alone?

Spring

 

[jrutler]

Just checked the filter. It was stopped again. I opened up the valve and (for the first time) smelled the rotten-egg sulpher.

I opened the valve very slightly and put the output directly into the input of my skimmer. I think that I read that this is a good idea.

I took the effluent from the filter and compared it to the tank water. Nitrates: 0ppm (coil), 30ppm (tank). Wow. I was suprised at the difference, but concerned about the sulpher.

I need to get this thing working consistently. I had bought a dosing pump for this purpose a few months ago. It was the used medical kind. Worked fine, but needed to be reset twice a day because its maximum dosing volume is 1 Liter. Complete unreasonable PITA

The doser will soon be working on iodine or some other trace element, but I still can't get a consistent flow on the coil filter.

I'd appreciate any suggestions.

 

[traveller7]

1. Get a great Nitrate and pH test kit

you should be testing nitrate and nitrite, ive not heard of testing the output PH as a regular job???

Effluent in my denitrator systems tends to be very acid. Depending on the ability of an individual systems ability to buffer, I prefer to monitor the values. Especially on my smaller systems.

 

[rsman]

smelled the rotten-egg sulpher.
probibly no big deal but next time open it up fully and toss the output water until the smell goes away

I opened the valve very slightly and put the output directly into the input of my skimmer. I think that I read that this is a good idea.

its a good idea even if you dont have the sulpher smell

I took the effluent from the filter and compared it to the tank water. Nitrates: 0ppm (coil), 30ppm (tank). Wow. I was suprised at the difference, but concerned about the sulpher.

your unit is probibly cycled just fine, you should step up the speed over the next say 6 weeks(slightly educated guess) from a few drips per second to wide open.

I need to get this thing working consistently. I had bought a dosing pump for this purpose a few months ago. It was the used medical kind. Worked fine, but needed to be reset twice a day because its maximum dosing volume is 1 Liter. Complete unreasonable PITA

its only needed when the unit is cycling your done cycling you just need to re introduce it to your system because of valve problems, once its done it should run full open. you can even remove the valve but only if you can easily put it back in the event of it getting cloged.

The doser will soon be working on iodine or some other trace element, but I still can't get a consistent flow on the coil filter.

good use for them

I'd appreciate any suggestions.

HTH