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Discussion Starter #1
Ok, I've been reading about diy coil denitrators and have a general idea.

75' of air tube is coiled around the inside edge of a 4" pvc pipe. the center is filled with bioballs or other media to create lots of surface area. the water flows at a drop or two per second down through the tube, then up through the media-filled center.

the idea is that water flows through the hose slowly enough that by the time it gets 3/4 of the way down the tube, the aerobic bacteria have used up all the dissolved oxygen. at this point the water is devoid of oxygen creating an environment for anaerobic bacteria to flourish and eat all the nitrates.

i've read that the 75' of hose would be good enough for a 75 gallon tank (or 75 gallons of water volume total). I havent found any instruction on how to make the device process water faster. Some have said more coils, others have said if you make the coil 10x longer, you can run 10x the volume through it and process 10x the nitrate etc.

Does anyone have any suggestions? I will have (when I get my new tank and everything) about 400 or so gallons total. I will need a denitrator for this much volume, but want the experience of building one and dont want to fork out the $$ to buy one that you just have to put media in all the time.

edit: also, nitrogen gas would build up in the unit i think. how would you let that out without letting any oxygen into the unit (causing you to cycle it again).
 

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youre last question is part of why this "technology" was given up on years ago, few people still wanna try it, i was one, but in all reality, it just isnt realistic, not only are you going to build up nitrogen gas in there but also hydrogen sulfides, which once those start to leak out into the system will kill everything in your tank.... you would be better off just putting a canister with GFO or something, unless you wanna exchange salt mix(by trading water change for this coil basically) for the eventual and inevitable crash of your tank.... esp using that slow of a drip rate..... the biggest short term problem youre also gonna have is that the water going into the coil must be one hundred percent filters, uved, etc, otherwise sludge, slime, whatever you wanna call it, will eventually clog it... this is the problem i had after about four months of using it, and since you cant open it or blast it out or anything there is nothing to do but trash it.... unless maybe you built it to be high pressure, and buy a high pressure pump....
 

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Discussion Starter #3
ouch ok. perhaps i'll give up on that idea. besides obvious water changes and running a refugium with macro, what other options are there to keep nitrates at (or as close to) zero? would running a reactor chamber with nitrate sponge media work well?
 

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What about letting the live rock work for you. Big powerheads on wavemakers. 400 is a big system. Do a search on "bill wynn big tank" and you will see his setup. Not sure if he describes 100% of his filtering methods but his is somewhere around 19000 Gallons!:blob:
 

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Discussion Starter #5
wow! ok i'll look that up. how much live rock would I actually need to keep nitrates at or around 0 with 400 or so gallons?
 

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depends on the density of the rock. Usually most people will say a pound to 1 1/2 per gallon of system. LFS owners might tell you 2 pounds. It is going to be expensive. If you have the time i would only buy a small percent of "cured" live rock like 5 to 10 and buy the rest dry base rock. A lot cheaper just takes longer for the dry rock to become live rock.

Another option is agrocrete. If you do a search on here about people making their own rocks and cooking them they will eventually become live rock and the bonus is you can make them the shapes you want. What i have read about, it is a whole lot cheaper but time intensive so....

i have also heard some good reviews about www.marcorocks.com

Wish i could remember the name of the company that was selling the agrocrete cultured rocks. You could probably find it in a search.
 

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Discussion Starter #7
i'll look into that. thanks for the info. so, what you are saying is...

if i use 1.5 - 2 pounds of live rock per gallon of water, that should keep my nitrates in check (as long as I do regular water changes etc). i wont need a nitrate reactor or anything like that? would a remove deep sand bed help any? i've read that those can become a sink and soak up nitrate and phosphate, only to leach them back into the system when it cant hold any more...
 

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the deep sand beds are preference but from what i have read, a practice from the past that is starting to be not as common as they once were. There are a lot of people on here that still use them and swear by them but there are a lot of people that will never go back to them. I prefer a shallow sand bed in the front of the tank and bare bottom in the back. I find it easier to clean. Some people just run complete bare bottom for convience of cleaning. good things and bad things from all options but i would say it is personal preference. I have a deep sand bed in my refugium but not in the display so.......

If you decide to go with a deep sand bed, don't disturb it after it's established. Like you said in the last post, it will release craploads of nitrates but i don't think it actually leaches them back into the system. When i rebuilt my refugium and dumped the sand from old to new, my nitrates immediately went to 80+ from the transition.

Lets see if anyone out there currently or previously using a deep sand bed has anything to add to this. I have never used on in the display tank so....

As far as the live rock goes, that will become your filter with the proper amount of flow and should contain your nitrate levels. Are you planning a sump or refugium or is this included in the 400 G?
 

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ive never used them just cause i figure were trying to keep the tank free of any dead spots and that is just a giant dead spot really.... but there are other, much more harmful things that can leach into the water if a DSB is disturbed, its just like the coil, can produce hydrogen sulfides too... among other things though, i dont do bare bottom cause i think that just looks bad, but i keep a thin layer, maybe inch and in some places two... i also like to use, tongika? i think, is the live rock that i filled my last tank with, totally "holey" so there is total water movement through the underside of the rock work..... really the only way to keep nitrate levels to a minimum is WC's, skimming organics compounds out of the water before they are broken down via the nitrogen cycle, which kind leads to water flow, by keeping the flow high and not letting fish waste and uneaten food particles sit within the water column, they dont produce nitrate, however, its almost impossible to have that great of flow, you would need power heads at all angles and on alot of different timers so that the flow changed all the time and and settled waste that had clinged onto rock would be blown off and skimmed out... having just two power heads works well though, i keep two koralias on in my 55 for twelve hours, then the timer kicks one off for six, and then the other off for six, and the other back on for that six, since theyre on opposing sides when one is off and the other is on, the current goes across the whole tank rather then meeting in the middle, thus making the current change and blowing anything settled up on that side.... but anyway, your LR is not really going to do anything but create a colony of bacteria, make a place to put corals, and be kinda a back drop of the tank, the amount of nitrate and what not that it would soak up would be minuscule unless were talking way down the road, so dont expect that to be where your filtration is... although, you do need it, for anything that is trapped in the rock for any period of time can break down into ammonia as we know and without the LR the bacteria needed to break that down would be much less sufficient...
 

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Discussion Starter #10
well i wasnt going to do a refugium. the tank I want is the marineland 300G deep dimension tank, and I was planning on a 75 gallon sump with a 50 gallon or so water change tank. if i used, say, a 55 gallon with nothing but a light and a big ball of chaeto (no sand), would that be enough to keep nitrates and possibly phosphates under control? also, would it be beneficial to have a phosban reactor if i had a refugium as well?

i'm getting that the rock will do some denitrification, but wont be enough to keep it at 0, which is the problem i'm having with my 75 gallon right now.
 

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One option since a 75 G is a decent size sump, is to make 1 chamber left for a refugium and chaeto, 1 chamber for your skimmer and phosphate reactor, then last chamber for your return.

With enough flow around the LR, sump skimming good, and the chaeto should control the nitrates and keep them at or near zero.

Why are you having trouble with your 75? Are you running a filter sock and keeping it cleaned? What is your equipment on that tank?
 

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Discussion Starter #12
well i have a 75 with a 29 sump and a 29 refugium (miracle mud and DSB) with some LR and chaeto and caulerpa. my sump has one baffle in it... tank drains to right chamber where skimmer is... that water spills over to the left chamber where return pumps are. mag 9.5 pumps water back to the display. mag 5 (tuned down) pumps to 29 refugium. refugium overflows back to the left sump chamber to bypass skimmer and not to kill all the pods etc.

my problem was that even with skimming and chaeto (skimmer was bad... 1 cup every couple weeks at best), my nitrates were waaay beyond 100ppm. the test said wait 3 minutes for color to develop... after about 3 seconds it was redder than the highest the color chart had, 100ppm. that was with feeding every other day too... and nothing died that was left to rot. i dosed potassium and iron (as the LFS said would help the chaeto) but not matter what I did, it wouldnt grow. I have a 75W equivalent CFL that was the color recommended by everyone on here... cant remember exactly right now... at the office. i've had the chaeto tumble, which tore up the sand/mud bed, i've had it static with huge amounts of flow from sump to fuge and back... and i've had slower flow with two powerheads to increase internal flow. only recently, after i added some caulerapa and stopped dosing, did i notice that the chaeto started to get bigger. my nitrates are at about 20-25ppm steady now, but i cant seem to get them any lower. would my best bet be to remove everything from the fuge and just run a barebottom chaeto tank with light and tumble it? or would it be better to run a sulphur nitrate reactor and get rid of the fuge completely?

oh, to answer your question, yes i have filter socks on all drains going from tanks to sump and i clean them out once a week when I do my water change. i also clean the skimmer at that point too.
 

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first off, LR will do no DE-nitrification at all, in order to make that happen within a tank there has to be an anoxic zone created, which was the original point of DSB's, i dont use cheato but dont you have to replace it over time? i could be wrong.... have you tried running your skimmer a little wetter? where is your bubble break zone at? the filter sock should be removed in my opinion but if you want one you really should be cleaning it everyday, every three days at worst.... i had my nitrate at about 20ppm about a week ago and its at 0 now, with no water change, just from dosing carbon.... my skimmer also works twice as good, look up carbon/vodka dosing... its not a substitute for WC but it works very well to eliminate nitrate and phosphate, just make sure that you do it for a few weeks to make sure the bacteria you create to soak up the nutrients doesnt have a sudden crash and send levels back up....
 

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Discussion Starter #14
i know you have to prune the chaeto, but replace it, im not sure.
the bubble break is about half way up into the collection cup... should it be more/less?
if i remove the filter sock, just siphon out the stuff that it collects?
carbon/vodka dosing... ok. could i do that continuously to keep nitrate/phosphate levels @ 0?
 

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yeah, actually you would be better off i think doing that, but you still are gonna wanna do water change to replenish any trace minerals that are used up, esp by coral....
 

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oh, to answer your question, yes i have filter socks on all drains going from tanks to sump and i clean them out once a week when I do my water change. i also clean the skimmer at that point too.
Just for an experiment, try cleaning the filter sock daily or every other day and after a couple of days, test your nitrates again. Filter socks are great at catching detrimus but if not cleaned daily will hold nitrates in. I had the same problem, nitrates always stayed at 20 ppm even right after WC's. I removed the filter sock and it immediately dropped to 0. I only use my sock during WC's now and just vacuum out the first chamber of my fuge when i do cleanings. Give it a try, might be the cheapest easiest fix.
 

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so here is a question for you, why would you want to use a filter sock? i dont see any reason if you have a skimmer, you dont wanna trap stuff before it can be skimmed out or you are defeating the purpose of a skimmer.....
 

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so here is a question for you, why would you want to use a filter sock? i dont see any reason if you have a skimmer, you dont wanna trap stuff before it can be skimmed out or you are defeating the purpose of a skimmer.....
Well they can pick up more solid junk than your skimmer does. If you have ever taken a powerhead or turkleybaster to your live rock and blow stuff around, the stuff that comes flying out is usually a little heavier and isn't picked up in the skimmer. I run my filter sock when i blow my rock off.
 
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