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

[Ciwyn]

No problem, I'm just repeating Donovans wisdom.

Yeah you've kind of taken over the reigns for him. I wish I had the chance to converse with Donovan as well. He seemed like such a nice person and what a brilliant idea he came up with!

 

[Colin_S]

Same here, I was really struggling with High no3 until I came across this thread. Read every post until the shock of his death... He seemed a genuine nice guy, willing to help and answered every question no matter how many times the question was repeated lol.

I think I've read it 3 times.. I understand the process and the build but he knew the science behind it all..

I think who ever used his method should/will help someone else. We've all used it because we all had issues at some point and it can be nervous without someone reassuring you who's already gone through it.
I posted the link to this thread on a UK forum and its helped a few people out.

I still use mine, does 1ml and the flow is high, but what happens is, eventually the bacteria builds up, the flow slows and the process kicks in. my no3 stays between 2.5 - 10ppm. Then I clean the effluent tube out and flow is back at 100%. Takes a few weeks to build up so it's easy to maintain. I check effluent every few days just to make sure it's not blocked.

Not sure I'm taking over the reigns just trying to keep the thread alive and help out where I can.

 

[Ciwyn]

So this is an interesting situation that is happening with the reactor now. The nitrates of the effluent has climbed way back up:

I'm guessing it had something to do with me playing with the drip rate. The effluent really slowed down as bacteria grew in there. I tried turning up the flow to break up some of the bacteria and allow some water movement through the reactor. The problem is on the input side if I turn the flow up water starts to build up above the cap on that side:

As you can see there is also a "gel" of some sort building up on this water. I'm not sure why that is.

So right now the effluent drip rate is about 10ml/min. Which if my math is correct that's in the ballpark of 10% turnover of my tank volume. I've increased my vodka dose today to see if that aids in bringing the effluent nitrates back down. I guess this is the tuning part of this reactor.

*Edit* Nevermind that drip rate is way too slow. It's only about 4 gallons a day. So the nitrates should be almost non existent in there. I also can't dial the flow up further because the water on the right side will start to flow over the top bypassing the reactor. I may have to try and get a good seal on the top of that side of the reactor.

*Edit 2* That layer of gel was definitely a bacterial colony. As I broke it up to try and get some more cement on the cap to seal it off better.


If anyone has any further suggestions or observations I'm interested.

 

[Colin_S]

apart from making sure your flow from the effluent is at 10%, and you dose your carbon you should be able to dial it back it. The slower the flow the more nitrification time. Keep in mind not to allow air back into the reactor.
The smelly bacteria will pass. I had it and most of us went through it. I placed a filter sock or coffee strainer on the effluent to catch the slime. Like you i increased the flow to flush it out, but only for short time, then put it back to 10% flow.

I had a similar problem with water back feeding through the dosing port caused by pressure build up. But I have a small pump used for GFO reactors so there is very little pressure to worry about. I read this was an issue so i made sure my tops of the reactor were screw tops and water tight. This way i can still access inside the reactor.

When you got the reactor at 10ppm, if it were me i would have left it be.

Just the other day i stopped dosing as my no3 is at 0,

 

[Ciwyn]

apart from making sure your flow from the effluent is at 10%, and you dose your carbon you should be able to dial it back it. The slower the flow the more nitrification time. Keep in mind not to allow air back into the reactor.
The smelly bacteria will pass. I had it and most of us went through it. I placed a filter sock or coffee strainer on the effluent to catch the slime. Like you i increased the flow to flush it out, but only for short time, then put it back to 10% flow.

I had a similar problem with water back feeding through the dosing port caused by pressure build up. But I have a small pump used for GFO reactors so there is very little pressure to worry about. I read this was an issue so i made sure my tops of the reactor were screw tops and water tight. This way i can still access inside the reactor.

When you got the reactor at 10ppm, if it were me i would have left it be.

Just the other day i stopped dosing as my no3 is at 0,

Ok so my NO3 has gone the opposite direction. It is currently very high coming out of the reactor. I diluted my salifert test with 2 ml of rodi water and the test was still very dark near the 100 color which would put the nitrate of the effluent near 300 if my math is correct.

 

[Ciwyn]

I forgot to edit my last post. My tank NO3 is about 75 ppm using the same dilution method.

 

[Colin_S]

from what i remember that is normal, like a cycling period. keep at it and it should start to drop.
read the thread from the 1st post, and i'm sure this is covered. It's well worth a read and you'll find load of excellent info

 

[Lazy8s]

I’m going to build my DND over Christmas for a water box 100.3. My towers can only get somewhere between 20-24in tall because of the stand. At that height does 4in vs 6in PVC matter very much? From the thread (read it all last night) it doesn’t seem like there’s a lot of aggregated data to know?

 

[Pny]

I'm also planning to build a Donovan style denitrator for my 1050 liter (275 us gallons) FOWLR over Christmas, (if I get my parts in time!). I will have two 90 mm diameter pipes (~3.5 inch diameter) and I probably end up with a slightly unsymetric design with 50 cm and 75 cm length of the pipes to have it fit my cabinet, (thats ~20 inch and 30 inch length). The internal volume will be a few inches more in height, since the fittings will extend a little bit further. I guess that's a little bit smaller than many other builds in this thread, but I hope it will be enough.

 

[Colin_S]

So from what i can gather, height is important as it allows the denitrification to take place. The diameter of the pipe not so important. Mine is 17" high and 110mm/5" ish in diameter.

Be mindful of not packing the media in tight. Flow is key and you want to avoid the media blocking the flow when the bacteria forms. So in my opinion a larger diameter will help with water flow, good size media and random shapes.

 

[Pny]

Can this reactor be used long term without bacteria build up / clogging and or sulfur smell, or is this a never ending balancing act with constant struggling of keeping the reactor in the right spot? Anyone using this method long term that can highlight us about the required amount of maintenance to keep a constant NO3 level in the tank using this method?

 

[Colin_S]

The sulphur smell is usually dealt with by increasing the flow, not too much that you're not getting the denitrification process but enough to stop the bacteria build up. So you can increase the flow and flush the reactor out for a few minuets then reduce the flow again.

From what I remember reading on the previous posts, when the reactor matures and you get a constant flow + dosing amount to reach your target no3 level from the effluent, the bacteria build should reduce and prevent it from smelling.

Not sure this helps but here goes.
My no3 was 160ppm for 2yrs or so. Using the DND I got it down to 0.25. My target from the reactor was 10ppm but despite testing nearly every day I went below. I did suffer from the sulphur smell which required me to clean the effluent tubing out, run the reactor at a higher flow for 15-20mins to give the reactor a good flush. This seemed to deal with the smell for a while until it repeated the cycle every week or so.

This was becoming a concern but then my DT hit 0ppm no3 which was not my intentions. I stopped dosing carbon (no-pox) and increased the flow, enough to prevent bacteria build up and no sulphur smell. For the last 2 months my no3 in the DT is still around 0.25 - 1ppm. my target is 5-10ppm.
I still have the reactor running in case no3 rises and I need to "turn the DND on", reduce flow and start carbon dosing. But so far my filtration, minus the DND is keeping up with my No3 levels.

So I've not run the reactor fully long term to see if it does in fact "settle down".
What I would do in any situations is.
Get your No3 in your DT to a level your happy with and just deal/ put up with the smell until the No3 level is acceptable in the DT.
Reduce your carbon dosing.
Keep the DND running and test your No3 in both the DND and DT making sure it doesn't rise.
This will tell you if you need to keep carbon dosing or at least how much you need to dose. You might find that you don't need to keep dosing long term which will result in less sulphur. or at least reduce how much you dose which might have the same affect with the sulphur. hope this helps

 

[Ciwyn]

So I haven't had an update in a while since not a lot has changed. I am currently dosing 34 ml of vodka a day into the reactor and the nitrates coming out high still. Probably still near 100. I have no idea what is going on.

 

[Aqua Man]

I am currently dosing 34 ml of vodka

What did you inoculate the reactor with? Which Bacteria strains? How tall is your reactor?

Maybe vinegar would work better?

There was another guy in this thread who could not get his to work either. I think he rebuilt it with different media inside for better flow. was able to get it working after that. His design was the U shaped one.

 

[Ciwyn]

What did you inoculate the reactor with? Which Bacteria strains? How tall is your reactor?

Maybe vinegar would work better?

There was another guy in this thread who could not get his to work either. I think he rebuilt it with different media inside for better flow. was able to get it working after that. His design was the U shaped one.

It was one of the bacteria’s in a bottle. I can’t remember which one at the moment. The reactor is 36” tall using 3” pipe.

I used some generic large ceramic rings as media. Bacteria definitely has grown in the reactor as I occasionally have to clear the effluent hose.

Nitrates have not changed or possibly gotten worse as I just did an ICP test on my tank and my nitrates are 237!

 

[Ciwyn]

Ok so this is odd. I have been doing pretty aggressive water changes for the past month and it appears to have made a large reduction to the nitrates in the tank. From the ICP test I had done where my nitrates were at 237 they now appear to be about 40. I used a salifert test today for that reading. I then checked the nitrates of the effluent on the reactor and they actually appeared to be a good bit higher than my system. They are definitely somewhere between 50-100. I'm guessing in the 80 range.
What would be causing this?

 

[Aqua Man]

Could be letting air in. If too much oxygen gets in then the bacteria can’t do the job.

 

[Warren_Jakarta]

Just an update - I stopped using mine for a bit (a year-and-a-half) because I found if you don't dose it doesn't work - I was travelling alot.
Last October (2020) I was curing some rock in water-change water (Brute G-can) and decided to plonk the DTD in there with an air-block and a small pump (6L/hr). I fed the thing two vials of that german stuff, dumped in a bunch (enough) LaCl, opened the DTD fullbore and walked away. For months. I came back a month ago and found my NO3 was pegged at 10ppm (down from 200 - long story). I dumped in half a cap of N0-P0X and 3 weeks later it was zero (Salifert).
I reckon the LL here is you gotta dose. (or perhaps I screwed up with dumping in the kraut stuff to begin with - I forgot the name).

 

[unchaotic]

I'm about a week and a half in now. This thing just kicked into high gear in the last day or two. On Saturday my nitrates were at about 30-40 ppm out of the tank and the destroyer. Now today we've got the tank results on the left and the effluent on the right. Looks darker in the pic but the tank looks to be around 15-20 ppm.

 

[bezj]

This is the best thread ever! Donovan was a genius!!

500 litre reef tank I built mine using some 18inch clear reactor chambers each holding 1.2 litres of media. Large/medium balls and rings linked by air line tube. went for this size to prevent clogging. Sump cabinet is dark so with clear is great to see what’s going on inside. Fine stream of water for flow rate.

Its been up and running for 2 weeks having seeded for 3 days with Aquaforest Bio S followed by 2ml x3 times a day of No-pox. No3 was 80ppm in DT. Just tested output and it’s 5ppm!

Very early days but very pleased!

Unsure of what to do next! Any thoughts??