Poor Man's Nutrients Control - Donovan's Nitrate Destroyer

[Gtinnel]

It’s not as big as the original DND calls for, this pipe is 2” OD. They are about 22 inches long

Hopefully you will still get an anaerobic zone but with only around 1/2 gallon of volume idk if you will or not.
Keep us updated with how it does.

 

[JonoH]

https://www.thingiverse.com/thing:2937243
Just found this!
Have been looking at putting one of these together, just to give more diversity for bacteria to populate my tank.

 

[Curiousbranching]

I’ve gone through every single page in this topic, and one thing really stands out: the time it takes for DND to start working seems all over the place. Some folks say it kicks in after just a few days, while others need at least a month before seeing any results. So I’d love to hear more detailed input from you all, so we can maybe gather some clever tips to help DND get up and running as quickly as possible.

I know a few people have already shared their setups, but I feel like beyond the basic how-to guides, there’s still room to make things even smoother and more effective.

For example—what’s the actual flow rate through your DND systems right now? I’m guessing it’s not necessarily tied to your tank size, because some of you with bigger tanks would probably struggle to hit the low-oxygen zone if you followed the 5–10%/day formula.

Looking forward to hearing all your thoughts—and may the nitrates drop ever in your favor!

 

[Curiousbranching]

So, my DND system has been running for 7 days now, but I haven’t seen any nitrate consumption yet. According to my hanna test, NO3 is still hovering in the 25–50 ppm range in DT, 50ppm in DND!!!. Naturally, curiosity got the best of me, so I decided to pop open the first chamber to see what’s going on inside.

The moment I opened it—bam!—got hit with a strong sulfur smell and saw a ton of bacterial slime. Uh-oh, did I set the flow rate too low? I’ve been running it at 5ml every 10 seconds, and maybe that’s just too slow for my tank size?

From what I understand, the first chamber is where most of the oxygen gets used up—so in theory, it shouldn’t smell like sulfur yet, right? Is that logic sound?

Anyway, the scientist in me kicked in, so I grabbed my cheap microscope and took a sample of that slime to see if it was full of dead stuff or if something was actually alive in there. And to my surprise—it’s absolutely swarming with life! Billions of microorganisms of all shapes and sizes, doing their thing.

So now I’m thinking, maybe I just need to crank up the flow rate a bit and see if that helps steer things in the right direction.

I would appreciate any advice, thank you.

 

[twentyleagues]

So, my DND system has been running for 7 days now, but I haven’t seen any nitrate consumption yet. According to my hanna test, NO3 is still hovering in the 25–50 ppm range in DT, 50ppm in DND!!!. Naturally, curiosity got the best of me, so I decided to pop open the first chamber to see what’s going on inside.

The moment I opened it—bam!—got hit with a strong sulfur smell and saw a ton of bacterial slime. Uh-oh, did I set the flow rate too low? I’ve been running it at 5ml every 10 seconds, and maybe that’s just too slow for my tank size?

From what I understand, the first chamber is where most of the oxygen gets used up—so in theory, it shouldn’t smell like sulfur yet, right? Is that logic sound?

Anyway, the scientist in me kicked in, so I grabbed my cheap microscope and took a sample of that slime to see if it was full of dead stuff or if something was actually alive in there. And to my surprise—it’s absolutely swarming with life! Billions of microorganisms of all shapes and sizes, doing their thing.

So now I’m thinking, maybe I just need to crank up the flow rate a bit and see if that helps steer things in the right direction.

I would appreciate any advice, thank you.

Is there a constant slow trickle coming out of the second chamber? It does sound like its a bit to slow with the build up and smell coming from the first chamber. Whats happening in the second chamber?

 

[Curiousbranching]

Is there a constant slow trickle coming out of the second chamber? It does sound like its a bit to slow with the build up and smell coming from the first chamber. Whats happening in the second chamber?

I measured the actual flow rate at 5ml every 10 seconds, but it’s really more like a fast drip than a continuous slow stream. I haven’t opened the second chamber yet because I’m worried that letting in fresh air might mess with the anaerobic bacteria in there.

The sulfur smell only became noticeable when I opened the lid on the first chamber to take a look—otherwise, it wasn’t detectable.

Now I’m wondering: should I increase the flow to a true slow stream, or stick with the recommended 5ml/10s for now?

 

[twentyleagues]

I measured the actual flow rate at 5ml every 10 seconds, but it’s really more like a fast drip than a continuous slow stream. I haven’t opened the second chamber yet because I’m worried that letting in fresh air might mess with the anaerobic bacteria in there.

The sulfur smell only became noticeable when I opened the lid on the first chamber to take a look—otherwise, it wasn’t detectable.

Now I’m wondering: should I increase the flow to a true slow stream, or stick with the recommended 5ml/10s for now?

Obviously you have bacteria growing in your first chamber. I would increase flow for a bit until the bacteria colonizes both chambers. Growing anaerobic bacteria isnt typically something that happens "overnight". While I have not run a diy nitrate reducer I did years ago buy one and the first week or so as you inoculate it and after, the directions indicate flow should be a slow trickle coming out then to dial it back to see reduced nitrates out. While I know the build is a little different the premise is the same. The faster the flow the lower the reduction. Too slow and it could stop all together. Same with to fast.

Edit- Also amount of media and type will possibly impede flow as well.

 

[Curiousbranching]

Obviously you have bacteria growing in your first chamber. I would increase flow for a bit until the bacteria colonizes both chambers. Growing anaerobic bacteria isnt typically something that happens "overnight". While I have not run a diy nitrate reducer I did years ago buy one and the first week or so as you inoculate it and after, the directions indicate flow should be a slow trickle coming out then to dial it back to see reduced nitrates out. While I know the build is a little different the premise is the same. The faster the flow the lower the reduction. Too slow and it could stop all together. Same with to fast.

Edit- Also amount of media and type will possibly impede flow as well.

Thanks so much for the helpful input! I’m going to try increasing the flow a bit and see if that makes a difference.

Oh—and one more thing. Why is the NO3 level coming out of my DND at 50ppm, while my display tank is only at 30ppm? Could it be because the anaerobic bacteria in the DND haven’t kicked in yet and started doing their job?

 

[twentyleagues]

Thanks so much for the helpful input! I’m going to try increasing the flow a bit and see if that makes a difference.

Oh—and one more thing. Why is the NO3 level coming out of my DND at 50ppm, while my display tank is only at 30ppm? Could it be because the anaerobic bacteria in the DND haven’t kicked in yet and started doing their job?

How are you feeding it? I am wondering if you might be getting detritus in there from unfiltered water. Other then that might possibly be processing ammonia from somewhere. Maybe test your feed water for ammonia?

 

[Curiousbranching]

How are you feeding it? I am wondering if you might be getting detritus in there from unfiltered water. Other then that might possibly be processing ammonia from somewhere. Maybe test your feed water for ammonia?

I’m currently dosing 6ml of 80-proof vodka, split into 12 automatic doses throughout the day. The water going into my DND is pre-filtered through a foam pad. As for the RODI water, I had it tested via ICP not too long ago and everything checked out just fine.

 

[twentyleagues]

I’m currently dosing 6ml of 80-proof vodka, split into 12 automatic doses throughout the day. The water going into my DND is pre-filtered through a foam pad. As for the RODI water, I had it tested via ICP not too long ago and everything checked out just fine.

Yeah I meant from the display like take the feed line out of the dnd and test that for ammonia/nitrite. Its possible but not probable. I am wondering if there is something that is "rotting" on the prefilter left over food or fish waste maybe?
I know there are other biological processes that effect our waste cycling not sure why the output would be higher nitrate than the input other than something directly feeding the process. Its possible that bacteria exploded in growth like a heterotroph and the nitrate is from some of it dying off. Just spit balling here.

 

[Curiousbranching]

Yeah I meant from the display like take the feed line out of the dnd and test that for ammonia/nitrite. Its possible but not probable. I am wondering if there is something that is "rotting" on the prefilter left over food or fish waste maybe?
I know there are other biological processes that effect our waste cycling not sure why the output would be higher nitrate than the input other than something directly feeding the process. Its possible that bacteria exploded in growth like a heterotroph and the nitrate is from some of it dying off. Just spit balling here.

Logically speaking, it’s probably a combo of low flow rate + decomposing debris inside the DND + the anaerobic bacteria not being fully established yet—that could explain why the NO3 level at the output is higher than in the display tank. I’ll give it a bit more time and report back with an update later.

Thanks again for all your helpful comments!

 

[blazn]

Regarding the clogging issue, I experienced the same after around 18 month or so. I stopped dosing carbon for 3 days and then started the dosing again slowly ramping up. That solved the issue.

Thank you for mentioning your tip on reducing clogging! I also ran into the clogging issue after about 18+ months, so I'd expect that may be a somewhat typical expectation.

 

[Yodaman]

Hopefully you will still get an anaerobic zone but with only around 1/2 gallon of volume idk if you will or not.
Keep us updated with how it does.

If I can’t achieve an anerobic zone, I’m willing to upsize the tubing. These were available to me for no cost.

Maybe I could put 4 of them in series, depending on how well this packs into the sump

 

[Curiousbranching]

I’m super excited to share some awesome news from my DND reactor today!

Nitrate in the display tank has dropped to 19.5 ppm (measured with Hanna), while the output from the DND is showing between 5–0 ppm (Salifert) and 2 ppm (Hanna). I recently adjusted the flow rate to 10% of the total tank volume per day, just like everyone recommended — and boom, it’s working!

Huge thanks to all of you legends who gave me advice and support. Y’all rock!

And now, because pics or it didn’t happen — here are some shots of my setup.

 

[blazn]

I’m super excited to share some awesome news from my DND reactor today!

Nitrate in the display tank has dropped to 19.5 ppm (measured with Hanna), while the output from the DND is showing between 5–0 ppm (Salifert) and 2 ppm (Hanna). I recently adjusted the flow rate to 10% of the total tank volume per day, just like everyone recommended — and boom, it’s working!

Huge thanks to all of you legends who gave me advice and support. Y’all rock!

Awesome & congratulations! You have now graduated to the DND 'legend' level!

 

[Curiousbranching]

Awesome & congratulations! You have now graduated to the DND 'legend' level!

Oh no, there’s no way I could’ve pulled this off without you guys! I’m still just a student in all this — learning as I go.

Next step? Gotta hunt down that sweet spot where I can keep NO3 steady around 2–5 ppm. Sounds simple, but you know how reefing goes… it’s never just “simple.”

 

[blazn]

With your interest & enthusiasm, you'll find that 'sweet spot' in no time.

Getting to the point you are now at is the big win...you know what got you there and it's just about making minor tweaks as you go along from now on. Long term, once you have your DND basically on auto-pilot (just making minor tweaks to flow & carbon input rate), you'll just need to watch for signs of any clogging, which based on my experience & those who posted recently, seems to happen around the 18 month point. I resolved that by 'flushing' my DND with RODI but someone else recently posted that they solved it just by stopping their carbon source for several days, which would be the easier route.

Thank you for your valuable input to this post!!

 

[McPuff]

Hi all! Adding my own experience to the thread... I just set up my own DND a couple of weeks ago and got it online about 9 days ago. It's a pretty big reactor as I used 4" pvc (~24" high and 20" wide). There are about 8.5kg of media inside. My system is approx 300 gal of actual water (300DD, 75g attached "lagoon", 80g sump). Nitrates were ~200 (yes, that high!) when I last sent in to ATI. I dosed prodibio for 5 days and decided to dose vinegar as the carbon source since I already have it on hand. Just doing the 5ml / day and have been dosing for 4 days so far. I haven't yet seen any bacterial slime appear at the effluent line. My flow is about as low as it can go without dripping but given the size of my reactor it may still be too early to see strong results. After looking at the posts higher on this page, it got me thinking that maybe I should check the input pipe to see how the bioballs look. If not today, I'll at least check it sometime this weekend. Then I can assess if I actually need to increase the flow which could very well be the case. I haven't yet measured the effluent but will do that today. Here is a pic of the reactor when I first set it up. Pretty simple!

 

[blazn]

Welcome to the DND club McPuff! Looks like you're on the right track, just be patient and it will definitely pay off!

Now, I haven't dosed vinegar myself, just vodka, but I believe that they recommend about 7ml/8ml of vinegar compared to 1ml vodka for the same amount of carbon input. So, I'd expect that you'll need to increase your vinegar dosage to get things moving. As an example, with about 120g total system, my maintenance dose of vodka is 4-5ml/day, whereas my dosage fluctuated up to 20ml/day while I was getting it going.