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

[McPuff]

Yes, I noticed this during the process of putting the DND into operation a few months ago. In the first month, I frequently experienced clogging in the DND outlet due to bacterial buildup. Although NO3 and PO4 in the tank decreased, I knew it was due to heterotrophic bacteria. Therefore, I reduced the flow rate to about 1–2 drops per second and divided the carbon dose into smaller amounts, setting it to automate 8 times per day, 0.3ml each time. After about half a month, I no longer observed bacterial accumulation in the outlet, and my NO3 dropped from around 40–50 ppm to 0–5 ppm.

Well, this might explain why I haven't seen a significant decrease in my system yet. The snot coming out of the effluent tube has definitely slowed (doesn't seem to be clogging anymore) so I'm taking that as a good sign given what @Curiousbranching has written above. I'll have to test it again this weekend to see what kind of progress is being made. Right now I'm at 30ml/day vinegar and flow rate is the thinnest stream I can get. Still haven't taken the algae reactor offline but looking forward to doing that.

 

[Levinson]

My DND is sitting inside of my tank and the effluent hose is placed right infront of the return outlet. So the effluent is dispersed into the tank via the return flow which then gets to the filter floss.
It is just a hypothesis at this stage but I have noticed my filter floss getting the tint of redish color after I dose carbon into the DND. Also, it seems like the floss (which I don't change often) become cleaner when it gets tinted in this redish color. It is just a feeling but the dark gunks on the floss seem greatly reduced.
I thought maybe this is due to the PSNB bloom inside the DND. So I asked the gpt (without mentioning the PSNB) and it also thought PSNB bloom was the most likely.
I have seen the floss turn red-ish before many times but I just thought it was odd and haven't thought of the carbon dosing as the potential cause until just now. I have yet to test the hypothesis that carbon dosing casues this coloration of the filter floss becuase I have only thought of it now but I plan on checking it out next time I dose carbon.

 

[Curiousbranching]

My DND is sitting inside of my tank and the effluent hose is placed right infront of the return outlet. So the effluent is dispersed into the tank via the return flow which then gets to the filter floss.
It is just a hypothesis at this stage but I have noticed my filter floss getting the tint of redish color after I dose carbon into the DND. Also, it seems like the floss (which I don't change often) become cleaner when it gets tinted in this redish color. It is just a feeling but the dark gunks on the floss seem greatly reduced.
I thought maybe this is due to the PSNB bloom inside the DND. So I asked the gpt (without mentioning the PSNB) and it also thought PSNB bloom was the most likely.
I have seen the floss turn red-ish before many times but I just thought it was odd and haven't thought of the carbon dosing as the potential cause until just now. I have yet to test the hypothesis that carbon dosing casues this coloration of the filter floss becuase I have only thought of it now but I plan on checking it out next time I dose carbon.

As far as I know PNSB only works in the presence of light. So it would be strange if there was any PNSB activity in DND related to NO3 removal.

 

[McPuff]

Small update on my DND: vinegar dosing is up to 60 ml/day and I'm still hovering around 50 ppm nitrate on the effluent. Rather than move forward with more and more vinegar I'm going to carefully make the switch to vodka dosing since it's a "stronger" carbon source and will mean much less dosing required (1/10th). Over the next 6 weeks I'll step down the vinegar and add vodka. Example: week 1 - 50ml vinegar/1ml vodka; week 2 - 40ml vinegar/2ml vodka; etc.

I haven't decided if I'll entirely remove vinegar dosing or not. If I get to 10ml vodka/day then I would only add vinegar after that point.

I know that vodka will not allow for as precise of adjustments as vinegar but I have a lot of nutrients, a large reactor, and a large bioload so I'm not worried about crashing my nutrients especially if I move slowly.

Has anyone else switched from vinegar to vodka dosing? Or just started out with vodka?

 

[Curiousbranching]

Small update on my DND: vinegar dosing is up to 60 ml/day and I'm still hovering around 50 ppm nitrate on the effluent. Rather than move forward with more and more vinegar I'm going to carefully make the switch to vodka dosing since it's a "stronger" carbon source and will mean much less dosing required (1/10th). Over the next 6 weeks I'll step down the vinegar and add vodka. Example: week 1 - 50ml vinegar/1ml vodka; week 2 - 40ml vinegar/2ml vodka; etc.

I haven't decided if I'll entirely remove vinegar dosing or not. If I get to 10ml vodka/day then I would only add vinegar after that point.

I know that vodka will not allow for as precise of adjustments as vinegar but I have a lot of nutrients, a large reactor, and a large bioload so I'm not worried about crashing my nutrients especially if I move slowly.

Has anyone else switched from vinegar to vodka dosing? Or just started out with vodka?

I used the nopox diy version and added a little yeast extract.

 

[McPuff]

I used the nopox diy version and added a little yeast extract.

This is the fuel I assume?

Also why add the yeast?

 

[Curiousbranching]

This is the fuel I assume?

Also why add the yeast?

Yeast extract is very effective in bacterial propagation, you can quick google about it.

 

[McPuff]

Yeast extract is very effective in bacterial propagation, you can quick google about it.

I guess what I mean is did you start out with that when you set up the reactor? Or did you add when transitioning to a different carbon source?

 

[blazn]

Has anyone else switched from vinegar to vodka dosing? Or just started out with vodka?

I've only used vodka to fuel my DND and I've been very pleased with the results. For the last year or so, occasionally I'll adjust it a ml/day, but typically between 4-6 ml/day of vodka maintains NO3 at 5-10 (on a 120g DT) with pretty heavy nutrient input.

 

[Curiousbranching]

I guess what I mean is did you start out with that when you set up the reactor? Or did you add when transitioning to a different carbon source?

Yes, I added it right from the start of setting up DND

 

[McPuff]

I've only used vodka to fuel my DND and I've been very pleased with the results. For the last year or so, occasionally I'll adjust it a ml/day, but typically between 4-6 ml/day of vodka maintains NO3 at 5-10 (on a 120g DT) with pretty heavy nutrient input.

Excellent, thanks for chiming in. I think I'm fine once the nitrates get down to 20-ish and then I just have to worry about the phosphates. Still need to dial in the GFO... don't really want to go with lanthanum.

 

[blazn]

Excellent, thanks for chiming in. I think I'm fine once the nitrates get down to 20-ish and then I just have to worry about the phosphates. Still need to dial in the GFO... don't really want to go with lanthanum.

I'm with you on the lanthanum, as that just seems a bit too risky for me. I use GFO in a reactor and it does the job. Just wish GFO hadn't got so expensive!

 

[Levinson]

As far as I know PNSB only works in the presence of light. So it would be strange if there was any PNSB activity in DND related to NO3 removal.

My understanding is PNSB are capable of different metabolic modes: photoheterotrophy (with light), but also “chemoheterotrophy or mixed heterotrophy” in lower‐light or dark conditions.
I think they are called 'facultative phototrophs'.

This is an article about it, though I cannot fully understand it.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11730080/

 

[Lasse]

Has anyone else switched from vinegar to vodka dosing? Or just started out with vodka?

Denitrification have been done in the waste water industry since the seventies (1970) All scientific reports I have seen state that ethanol is the most efficient carbon source for the classic denitrification. Vodka is only a trade name for ethanol with higher content of alcohol than 40 % I use around 24 ml 8% ethanol (cheapest Vodka I can find) to my reversed flow sand bed. 80 G and rather heavy loaded. The NO3 concentration is depended of how much I dose - above 24 ml - around 0-5 mg/L and below 24 ml - around 5-10 mg/L. 24 ml 8% vodka is around 5 ml pure Vodka. I prefer to dose a daily high amount of low concentration - with other words small doses - many times a day.

Sincerely Lasse

 

[JGT]

So finally decided to build my DND. Decided I wanted to run it outside of the sump so did some leak testing and all was good. Figured I’d seed it by running it out of a bucket to start. I didn’t have any MB 7 on hand but I did have a small amount of MB Clean (like maybe 50ml) so figured I’d start with that and dumped it all on. Added in around 5 ml of DIY nopox (vodka/vinegar) and started the pump with a very low stream. After 2 days the water got cloudy and after about 4 days it’s super cloudy which I figure is the bacteria. All I did was add about 5 ml of nopox each day. Just surprised it formed that quickly and heavily. I’m thinking the media must be getting inoculated with the bacteria as well. Just not sure how long it will take to fully saturate the media with bacteria. I guess doing a nitrate test and when it comes back at 0 I’m good to go?

 

[McPuff]

I have started to transition the carbon source from vinegar to vodka. It'll mean each week I remove 10ml/day of vinegar and add 1ml/day of vodka until I am only dosing vodka. It's possible I continue to dose both in the end to try and give myself a little extra wiggle room. Haven't tested NO3 in over a month but I'm seeing some positive effects in the displays. That should continue as the reactor continues to mature.

 

[Levinson]

Has anyone tried or thought of placing bio pellets in the DND? The idea is to have them slowly release carbon in the DND. I have read they can still release carbon in anaerobic condition and does not need to be tumbled though the release will be slower.

 

[McPuff]

Has anyone tried or thought of placing bio pellets in the DND? The idea is to have them slowly release carbon in the DND. I have read they can still release carbon in anaerobic condition and does not need to be tumbled though the release will be slower.

My concern is the size since they are very small pellets. Even with the 1" bio balls I'm using, the reactor will get a bit clogged. My guess is bio pellets would create a pretty dense mat that would clog very quickly in the absence of tumbling.

 

[McPuff]

How are others dealing with reactor clogs? I have dealt with effluent line clogs and that is pretty easy. But now my reactor seems to be humming along pretty nicely and the flow-through is the "issue." Water is flowing back out the input ports (in small amounts). If I open the input line to full flow and try to flush the reactor a bit it does help but only for a day or so.

Good news is that my nitrates have gone down quite a lot. They are now down to 60 (yes, this is actually quite low for my reef over the past few years... it was over 200 last year) so the reactor is working pretty well. I think the switch to vodka has made a pretty significant difference as most of the decrease in NO3 is in the last 2 months. Right now I'm dosing 20ml vinegar/day and 4.4ml vodka/day. I'll increase vodka to 5ml/day and see how that works. If I can remain stable around 20-30 I'll be happy. The bigger goal now is to get PO4 down substantially (it's at 1.5). I may need a better GFO reactor...

 

[blazn]

Great news on the NO3 reduction and the possibility that changing to vodka may be improving the results of your DND!

After about 18 months of use, my DND started to clog and I removed it from my sump, separated the two columns and flushed each with RODI water a few times. I found that most of the visible bacteria growth was in the input/first column. That was back in May and I haven't had it clog since then, but I expect I'll need to flush it every 12-18 months. Someone else in a post on this thread, later last year, indicated that they stopped dosing vodka for 3 days and that was enough to clear their 'clog'.