My Homebuilt Coil Denitrator Works!

[sam1174]

I was having nitrate problems because I have too many fish and I give them too much to eat. Nitrates were hovering around 40-50, even with frequent water changes. I did the sugar thing, which dropped them down to 10, but I wanted them at zero, so I built myself a coil denitrator for about $40. It had been up and running for 3 weeks with no effect, and then it finally kicked in! My nitrates are now ZERO!

Here's how I built it:

Wal-mart sells these large plexiglass jars with lids that clamp down. I bought one of those ($6) and a spool of 3/8 inch tubing at Lowes ($8). I also bought these cool connectors that I had never seen before. The tubing slips in, and is locked in place. I bought three connectors for the lid ($12). It took three because one of the connectors needs to have tubing connected to it on the inside of the lid as well as the outside. I drilled the holes and screwed the connectors to the lid using silicone to seal the holes.

I then cut off 15 feet of tubing and carefully coiled it into the jar. I then filled the bottom half of the jar with aragonite sand, and the top half of the jar with bio balls. I don't know why I used sand and bio balls, it just seemed like it would work. I also sprinkler some of that dried bacteria dust into the sand and balls to give everything a jump start.

The coiled tubing only needed to connect to one of the connectors in the lid, so I plugged it in, and then sealed up the jar. The jar has a rubber gasket around the lid, but I sealed it up with silicone, too.

(To be honest, the first time I tried it, water started squirting out from around the gasket. I had to drain everything, dry it off, and seal it with the silicone a little later.)

I then added an in-line valve to control the water flow and connected the supply tube to a little tiny fountain pump I bought at Lowes for $18. After the jar filled up with water, I adjusted the flow to 1 drop per second and then I just let it sit.

I had been checking my nitrates just about every day, and they were hovering at 10 ppm. I was out of town for three days, but when I check the nitrates in the tank tonight, they were at ZERO! It really worked!

I spent more time chasing down parts than I did actually building the thing. It looks ugly, but it is cheap and effective. I'm thinking about buying some lexan tubing and rebuilding it to make it look pretty, but for now it is serving it's purpose.

[jgb23]

Can you post a photo of this? Sounds intersting and would like to look at doing this.

[drummereef]

[Coyle]

tagging along for the pics..

[kh6sat]

This site may help out with plans.
http://saltaquarium.about.com/b/a/094930.htm

[Boomslang]

How large is your tank? With 1 drip p/s all your tank water would never have passed through your denitrator in 3 days, so how could it be on zero nitrates, except if something else helped as well..... maybe I am wrong, if I am I want to build myself one as well...

[cristhiam]

Did you test the water coming out from the denitrator? Mine took about 2+ months to start working and was not enough for my 125G also I think 15 feet of coil is not enough, and the sand is not needed, just the bio balls. For the size of you tank you probably going to need about 75'. Here is a thread about coil denitrator and how effective they are http://archive.reefcentral.com/forum...hreadid=470701

[sam1174]

OK, here is a picture.

The ball valve with the blue handle is on the supply line, the other tube just drops back into the tank to return the water. When I tap on the jar, I can see bubbles rise to the top through the sand and bioballs, I'm assuming this is the nitrogen that is formed by the anaerobic bacteria.

In regards to boomslangs comment, I have a 75g tank. I just tested the water again. I tested both the water coming out of the denitrator, and the water in the tank itself. The water coming out of the dentitrator test a bright yellow, definitely 0ppm. The water in my tank looked like zero when I first tested it, but now that I see it compered to the water straight from the denitrator, it is a slightly different shade, but not even 5ppm. I'd guess 2ppm, but my test kit isn't that sentitive. The difference in color between the two tests is miniscule, though. I might be dripping slightly faster than 1 drip per sec. It takes about 15 seconds to fill up a 5ml vial. That equals 20ml per minute, 1200ml per hour, 28800ml per day. There are 283875 milliliters in a 75g tank, so you're right, there is no way I could circulate the whole tank through in 3 days. It would take a minimum of ten, and that doesn't account for the water that gets recirculated back through the denitrator. However, I don't know what else could account for the sudden decrease in nitrates. I've been battling the high nitrates for months, and suddenly they are gone.

[Boomslang]

Like you, I would be just as glad that something worked, doesn't really matter what.... I think I will build one, I will just make it larger (With more water volume at the same flow, the water/bacteria will have more time to loose/use the O2.....

[sam1174]

I just thought of one other thing. I installed a phosban reactor about a week ago. I've never heard that it has an effect on nitrates, though. My phosphates were at 1ppm and now they are indetectable.

[kimoy]

i don't think that that DIY has already finished the cycle. i think that your nitrates went down is because you left your tank for 3 days without feeding and if recall it correctly on your first post that you feed a lot. that is enought time to get nitrates down to 0 from 10. i am not saying that this doesn't work but i think it still needs some time to cycle. but if i am wrong good job and congrats on getting your trates down.

[jgb23]

So I have been reading up on this post and a couple others. Does the hose coil around inside and output at the bottom of the tube and the water filters up through the sand, bioballs, and finally out the output tube? I read some post that had the whole column filled with plastic tubing but stated the water left the tube in the middle of the column, not at the bottom.

[sam1174]

Originally posted by kimoy
i don't think that that DIY has already finished the cycle. i think that your nitrates went down is because you left your tank for 3 days without feeding and if recall it correctly on your first post that you feed a lot. that is enought time to get nitrates down to 0 from 10. i am not saying that this doesn't work but i think it still needs some time to cycle. but if i am wrong good job and congrats on getting your trates down.

I have to disagree. I have bubbles coming out of the sand (nitrogen) and the output of the denitrator tests bright yellow on the nitrate test kit. I have the tank on an automatic feeder because I frequently go out of town for three or four days at a time. There was no change in the feeding habits while I was gone. If anything, I would have expected it to be a little higher because I always give them a little extra just before I go out of town, just in case the automatic feeder breaks.

[sam1174]

Originally posted by jgb23
So I have been reading up on this post and a couple others. Does the hose coil around inside and output at the bottom of the tube and the water filters up through the sand, bioballs, and finally out the output tube? I read some post that had the whole column filled with plastic tubing but stated the water left the tube in the middle of the column, not at the bottom.

Yes, the flow comes in from the top, coils around a bunch of times, and ends at the bottom. I figured that was the best wat to do it because (theoretically), by the time the water gets to the sand, it should be devoid of oxygen.

Also, I used sugar originally to get my nitrates down. I gave my tank a final dose of sugar about the same time I started the denitrator, and I did it by turning up the flow on the denitrator and allowing the pump to suck the sugar water through the denitrator. Perhaps the sugar, and the bacteria powder that I put in the denitrator, jump-started the cycle.

[aninjaatemyshoe]

"sand is not needed"

Actually, if it is aragonite sand it would help keep the unit from decreasing the pH too much from the denitrification. It would also have the added benefit of raising calcium a bit. I would use medium sized coral fragments instead of the sand however. The bioballs will help, but you'd probably do better using sulfur media instead. The denitrifying bacteria need an energy source for them to metabolize. This would usually come from miscellaneous protein waste, but if your nutrient level is low it may slow down the denitrification. This is also the theory that drives the vodka/sugar dosing method.

[Europa13]

The bio-balls will turn the denitrator into a nitrator soon if you don't clean them weekly...

[aninjaatemyshoe]

The bio-balls will turn the denitrator into a nitrator soon if you don't clean them weekly..."

Bioballs only produce large amounts of nitrate when they are in the presence of oxygen. The purpose of the coil denitrator is to remove the oxygen before it hits the chamber so that anaerobic denitrification can occur. Really, all bioballs are is a surface for bacteria to grow on. They really aren't necessary unless you really need to process a hole lot of crap with bacteria (as in waste processing plants and large fish facilities).

[sam1174]

Originally posted by Europa13
The bio-balls will turn the denitrator into a nitrator soon if you don't clean them weekly...

Normally that would be true, but that is not the case with a coil denitrator. The flow is so slow that the nitrates are broken down into nitrogen and... uh, something else, before they are released back into the tank.

Also, cleaning the balls would defeat the purpose of the denitrator. You want the anaerobic bacteria on the balls in order to brake down the nitrates. In a wet/dry system, you have aerobic bacteria on the balls, not anaerobic bacteria. The aerobic bateria create the nitrates. The balls in a coil denitrator are populated by an entirely different breed of bacteria, and they break down the nitrates..

[willhoward]

This is the first time I've heard of dosing your tank with sugar to lower the nitrates! How exactly is this done? By just adding sugar into the water? How much sugar per gallon?

Thanx

[tgreene]

I've always used Vodka, but the principal is the same... Europeans have been doing it for decades!

[ronert]

i thought the vodka was for me ... no wonder it had no effect on the water parameters ...

[WhiskeyReefer]

Originally posted by ronert
i thought the vodka was for me ... no wonder it had no effect on the water parameters ...

lol, funny, ronert I was thinking the same thing. But can you please tell us how to apply the sugar to the water and how do you determin how much you need?

[sam1174]

1/8 teaspoon per 25 gallons (tank and sump combined). So for a 75g tank with a 25g sump you'd use 1/2 teaspoon.

Do a search on this board before you do it. People divide into two groups on this sugar issue, one swears by it, the other says if you use sugar you will tear a rift in the fabric of space and destroy the universe. I don't believe them.

[willhoward]

So for a 65G it would be:
1/8 x 2.6 = 26/80 = 13/40 ~ 12/40 = 3/10 ~ 1/3

How could a third of a teaspoon make a difference in so many gallons of water? What exactly does the sugar do?

Thanx

[Engine 7]

I might just have to make one of these now. Thx a lot for the info