Coil Denitrator

[rsman]

ok so sometimes the brain cells in my head rub together a little late

another denitrator
if your not into DIYing your own. ive had good results with one of these, not on my breeding setup, but on two of my display tanks. consider it just like a protein skimmer, over rated by about 200% when using in a breeding setup

 

[rsman]

so JHardman it seems like its been 2 weeks so whats your driprate how much nitrate in the source and output water, and any nitrite ???

 

[olin]

I've tried the coil denitrators and have had great success...until they clog. And they always do. What happens is that the bacteria secrete a biofilm which is an exopolysaccharide (snot) which continues to grow until there is no more space. I made a super simple denitrator that has been working like a charm for over a year with no troubles, and a has few benefits over the coils. I just took a salt bucket, and stood up a 3 foot section of 3" PVC with a "T" connector on the bottom. I filled the bucket with silica play sand. Then I just started a siphon from the tank with airline tubing into the stand pipe. The water runs down the pipe and slowly percolates up through the fine sand. There is a huge amount of surface area here and the water can channel itself around obstructions. The added height of the pipe can give extra pressure from gravity if there are clogs. I placed mine in my sump so the filtered water just runs over the sides of the bucket, but a drilled overflow at the top could also be easilly be used. Since I added this, my tanks are at 0 nitrates (Even my clownfish growout systems). About a year ago, I changed the media to sugar sized aragonite, and now I don't have to add calcium anymore either because the low pH dissolves the CaCO3! Total cost with the silica sand was $8. I just replace the 2 foot airline tubing now and then when the flow slows. No H2SO4 or odor have been noted either.

 

[Fredfish]

Interesting setup olin. I can't quite picture how the 3' section of pipe works. Is it full of water (I asume so)? If so, how to you control the water level inside the pipe? Is the pipe capped at the top?

Also, do you prefilter the water to keep particulate matter from acumulating in the sand?

Hmm. This opens up some interesting posibilities.

Fred.

 

[olin]

Oh, yeah, I also made the top 3" into a refugium be putting in some bits of small LR and an airstone and a handful of LS from the tank on top of the sand. Tons of pods!

 

[olin]

Hi Fred, the PVC is just stuck in the sand to the bottom of the bucket. The airline siphon just runs into it, so the water finds its own level. This could even be done without the pipe just by running an airline siphon straight to the bottom of the bucket, I just used the pipe because I figured the airline might get clogged with sand and when the airline needs replacing, it is easier than digging through sand. Also, the added height will give extra pressure if the filter gets slow to trickle. As the water backs up in the pipe, it gets higher and forces its way down again. I haven't had mine slow down in over a year, so the pipe is probably optional. Yes, thanks for reminding me, I do wrap some filter floss (Heater filter material- the blue/white stuff) around the intake to minimize particulates.

 

[Dman]

olin,
pics please, I think I have an idea, but I want to (like everything else in this hobby) make sure. The 2 foot airlinme tube is just that, the 1/4 inch stuff, right?

My original idea was to string three house filters together, fill'em with a bio material, like bio-balls or those ceramic thingies the Fluval uses and let 'er rip.

Dman

 

[Fredfish]

OK, makes sense now.

Did you have to start you have to start your denitrator the way rsman did, or did you just start the syphon and leave it alone?

Fred.

 

[rsman]

im a big fan of coil denitrators over most alternatives, Id like to think that my being a fan is based on both personal experience and the research ive done on/with them. hopefully its not to based on my experience alone. I dont build them for others, I dont sell them, I just like removing nitrate by any means other than waterchanges. there acually are better methods, but some are very cost prohibitive and most both IME and in research require more maintanence. as a single example there is one used by food fish farmers that uses electrical plates it removes all nitrogen in any form in a single pass, though those plates need power, and the evaporation is increased dramatically, and normal replacement parts need to be on hand ..... it becomes less in the interest of a small time breeder (im guessing here but id say that as fish breeders every single ornamental breeder either the guy in the garage like me or the nice people at ORA are a small scale breeder compared to many food fish farmers)

now after kinda putting my point of view out there, the bucket full of sand aproach has been done before, and along with its advantages it has some disadvantages, one of which is it will create fine pathways or channels that the water will travel thru and this will cause the bed to crash, eventually. there are some work arounds and replacing the sand from my recollection is the best followed by mechanical stirring(memory of broken units pops to my head). I dont know that it needs to be done yearly or not, and ill guess that like many things it depends on things that are hard to compare like the quality of the input water, input rate, size of the chamber .....

now after stating that it might work well for a very long time in a fish breeding setup, but I like the coil still, as for it always cloging thats not really true, its close, but not really true, if the feed rate is high enough and a bio chamber is used, the chances of input tube cloging are significantly reduced, and to some point eleminated. ive been using a coil on a single tank without any maintenence for about 4 years now, though the bio load is nothing like a SW breeding setup, its a 55g FW tank with a handfull of platties its still running, and has been just fine.

as for cycling them you still have to cycle them, but it wont take as long and you dont actually have to do anything, just expect a short period of time before they start working.

 

[olin]

I agree, coil denitrators are a great way to go. I've been experimenting with them for years and they work great. In my systems which are heavilly stocked and very well fed, the heterotrophic bacteria like vibrio and pseudomonas predominate in the coils, and unfortunately, these are the biofilm makers. They also competitively inhibit the more beneficial nitrogen fixing bacteria, so in my tanks the coils quit too soon. I've experimented with flow rates, and in order to keep the biofilms down, the flow rates had to be increased to the point that the exiting water was microaerobic rather than the desired anaerobic/anoxic. So in my systems, they worked well but required too much maintenence for a lazy guy like me. But there are tons of systems and numerous "right" ways to do things. It is just a matter of finding what is best for your biosystems. As for the physics and microbiology of the sand system, in my opinion, the channelling is a desired effect. The water trickles through numerous channels, and passive diffusion and microbial cilliary beating moves nutrients out of the channels and into deeper portions of the sand where it is broken down into N2 (g), just like in live rock. I've checked this with ISE and culture. The sand seems to be "self stirring, as N2 bubbles out, the flow dynamics adjust and the nutrient flow varies from day to day between the different portions of the bucket. This may be due to the large amount of nitrate available for fixation, but I imagine it would work in most systems at different rates according to load.
As for the tubing, yes, just 1/4" tubing is the stuff. I don't have a digital cam yet (but the new Nikon D70 is looking hard to resist!!!) but I will try to borrow one. As for cycling, I just washed the sand and started the flow. Let the microbes do the rest. Every now and then I add a pinch of sugar to the standpipe. Don't know if it helps, but seems to kick phosphates down a bit. Maybe it's just wishful thinking....

 

[Fredfish]

I do like discussions that get me thinking. Ok, here goes.

rsman. I am continually impressed with your level of knowledge and the amount of research you have done. That example form the aquaculture world is cool. I did some digging around at a couple of local universities on aquaculture stuff but never came across any sources that provided a lot of practical info.

Olin. What size system are you filtering with your bucket. I am starting with 1 40 gallon tank and 2 pairs of fish (clowns & bangai) so I suspect I don't need a very big bucket.

On the sand bucket approach, what if you set it up like a fluidized sand bed filter (sealed of course) with a recirculating pump that you could cycle daily/weekly/monthly for a few minutes to stir up the sand. this should eliminate any long term channeling issues or clogging.

I don't know if this would be disruptive to the bacteria. I generaly think of bacteria as very hardy souls, but fluidizing the sand may disrupt the beneficial biofilms.

I suppose that stirring a little once a year might be a more practical approach though.

You could take this a little further and attempt to use a deep sandbed as a denitrator, but thats a discussion for another forum.

Fred.

 

[olin]

The system I have it on is a 90g parental tank, inline with from 4-8 20g growout tanks. I think the stirring thing every 6 mos-1yr might be best. You don't want to disturb the reduced oxygen areas too much. I kind of picture what is going on as this thing just being a 5 gallon chunk of live rock except the grains aren't fused. You have areas with active water flow, and others where it is static.

 

[rsman]

ive spent tons of hours searching/reading/banging head on desks ....

the bacteria isnt really hardy, and will become detatched easily, its one of many reason the bio chamber at the end of the coils works better.

with a 5gal bucket and only 250g total its possible it could take decades to have problems, its something I cant answer. those dead spaces outside of the channels are bad things. more so when the channels start to straighten out, at that point the bucket will luckly only fail to work. at some point those dead spaces will create H2SO4.

 

[Fredfish]

Hmm. Lets see if this sums up what you guys are saying.

Coil denitrator. Harder to start up and possibly more maintenance, but more controlled and less likely to crash.

Gravel bucket denitrator. Cheaper and easier to to set up and run but some risk of crash in the long run.

If I were to use a coarser sand or gravel, would that not increase difusion within the bucket and reduce the risk of a crash?

Fred.

 

[rsman]

i think the problem is you havent done it :bounce1:

its not really hard to do either, and the amount of work is soo minimal, to properly cycle both takes time, and a new coil is more likely to clog, the needle valve needs to be partially closed alowing almost anything to clog it, but its not really "hard" to check that water is dripping, nor is it "hard" to clean out the needle valve, once its cycled depending on the setup the needle valve can be removed, or mostly wide open and becomes less likely to clog. it still needs to be checked often, but thats clearly not "hard" its a simple is water coming out or not! with a well built and cycled coil its almost impossible to have water going in the in and out the out and have problems when its broken its clear where and what to do to fix it. with a bucket of sand it could create enough of those channels that it crashes, if that happens how are you going to know?? the dead fish?? thats a bad idea so whats next ?? if it were a DSB you could see the sides of the bed change, you cant see the sides of the bed if its in a bucket so your stuck manually stiring or replacing the sand bed, though its not really hard its maintenance, then there is the issue of how much do you stir, mix it up too much and you have to re-cycle the unit, along with getting a significant die-off, dont mix it enough and whats next it crashes and your in the same boat and you still have to monitor the output to make sure it doesnt stop. for whatever reason (murphy's law rules!!!)

the larger the sand size the more it takes and the slower the flow needs to be, your better off picking a size like recomended for a DSB.

to add to this, just today I finished building a new coil for another tank I have that doesnt have one, I took tons of pics, and will get a day by day and a "how to" thing done ill have some of it *maybe* in 2 weeks but I wont have it all for probibly 6 ish as the day to day ill list for the entire cycle time. its a small unit but the model will work for any size.

 

[WmTasker]

OK ... Jumping on the bandwagon here. I was planning on putting both a calcium reactor and de-nitrator coil on my reef. My question is ... Since the water leaving the reactor is already high in CO2 and low in O2, wouldn't it be easy to have that then fed into the denitrator? since the CO2 is high and the O2 is low, would I need 100ft of tubing? I was planning on having it fed into something that would help raise the O2 back to normal after that. Let me know what anyone thinks of this.

 

[rsman]

water in a ca reactor is not low in O2 its just high in CO2, however the coil's output is low in O2 and high in CO2, so you could put that into your ca reactor.

 

[Fredfish]

i think the problem is you havent done it

Hee, hee...

Yup. I'll be getting around to it soon. Need to drill my 2 40s so I can plumb them into a common sump first though. Need someplace to put that denitrator.

Fred.

 

[mattjk]

bump

 

[rsman]

is there a reason for the bump?? other than its a cool thread

if there is a new question, or further input requested, request it.

FWIW ive had my coil un attached to the majority of my breeding setup for about 3 weeks now (unrelated issues) my nitrates are out of the world, gona have to put it back asap. water changes aint gona happen too $$$$