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

[OverThinker]

any one have pump recommendations?

I got lucky today and scored all my PVC for free!

 

[twentyleagues]

any one have pump recommendations?

I got lucky today and scored all my PVC for free!

TBH I think a continuous duty dosing pump would be the best option, but really any small utility pump with enough gph/head pressure to get the water to the unit will work fine. This doesnt need to be fancy or expensive. Dont over thin......ummm yeah you know.

 

[Levinson]

I knew siprox release silicate in anaerobic conditions but I thought the top near the inlet of the DND wouldn't be so anaerobic so I placed some siporax there and filled the rest with other stuff. I didn't want the silicate level to go out of control. But it still did release silicate and I wasn't sure why but I think I have found the answer to this.

It was quite simple.
1. The carbon I dosed was vinegar.
2. Vinegar is very low in pH (acidic).
3. The siporax media is placed right below the dosing hole, so the vinegar was dosed right on top of the siporax media.

Of course, the vinegar's acidity would cause the siporax to release silicate!! I was dosing acid onto the siporax!
I feel stupid to not think of this sooner. My mind was so stuck on the 'anaerobic condition -> siporax releasing silicate' but it was 'anaerobic condition -> low pH -> siporax releasing silicate' so what was ultimately causing it to release silicate was low pH, not anaerobic condition.
It wasn't very scientific but I tested it by pulling out the siporax and the sponge growth slowed down greatly after a few days of pulling out the siporax.

The plot twist is, I realised that I actually like high silicate in my tank. I want that big diatom bloom and sponge growth again so I put the siporax back into the DND. Will have to wait and see if it will go back to how it was before.

It is back to how it was before. After a few days of putting back the siporax media and vinegar dosing, the sponges started to grow again.

 

[OverThinker]

TBH I think a continuous duty dosing pump would be the best option, but really any small utility pump with enough gph/head pressure to get the water to the unit will work fine. This doesnt need to be fancy or expensive. Dont over thin......ummm yeah you know.

Thanks, Ha ha ha that’s exactly how I came up with my forum name by the way

 

[Gtinnel]

I have been running one of these for over a year and to be honest I was never really impressed with it. In the beginning I constantly had flow rate issues, mostly caused by my bad choice in feed pump, and everytime I would test my output water’s nitrate level it wouldn’t be that much different than my tanks reading. Although to be fair I hadn’t tested it in a very long time and the thing has just been running without me doing much to it for a long time now.
A few weeks ago my feed pump died and I didn’t bother to replace it because I was convinced it wasn’t really doing much. Well since the pump died my tank has been completely taken over by hair algae, so I guess I was wrong and it was making a difference. Now I’m going to get it up and running again, and I’m even considering adding one to my other tank.
I guess I didn’t realize what I had until it was gone, lol.

 

[Dukereefnz]

I used Tee from a pump used for other stuff - put an inline tap on the in feed and it has been perfect.
Nitrate is 5.6 today... it is rock solid.

 

[ravi197699]

any one have pump recommendations?

I got lucky today and scored all my PVC for free!

I use coleparmer 80v dc peristaltic pump that I bought sometime back, flow can be controlled by solid state driver and flow can be fine tuned by controlling the speed to so low that it will drip water and max to stream of water. these pumps are bullet proof,

 

[Garf]

Any of you folk actually harvest the bacteria? ie. Remove and discard?

 

[pooootiqe]

I have modified my DND and added a small circulation pump and fluidized plastic media (like K1) inside close to the exit hole. The pump faces upwards to tumble the plastic media.
I have thought of the idea while learning about the EBPR (enhanced biological phosphate removal) system in wastewater treatment. The EBPR system uses bacteria and carbon to remove phosphate from wastewater and is used for freshwater treatment but I have read it can be done in saltwater as well (but I have not seen any examples of it being used in saltwater environment).
The idea of EBPR system is, that the PAOs (phosphate-accumulating organisms/bacteria) can bind phosphate in their cell when they are in an environment alternating between anaerobic and aerobic zones and when organic carbon is available for them in anaerobic conditions. From what I gather (which might not be 100% correct) when there is carbon available for the PAO bacteria to consume in an anaerobic condition, the PAOs will release the phosphate in themselves into the water while taking in the carbon (so the phosphate level in the water would actually rise) but when they are moved to an aerobic environment afterwards, they would use the energy stored from carbon to take in and bind more phosphate than they have released before from the surrounding water in their cell, ultimately lowering the total phosphate in the water.
I thought the conditions for EBPR systems are quite similar to the DND. The DND also has the water going from anaerobic (inside DND) to aerobic (outside DND) conditions. But for EBPR to work, the PAOs need to be moved out of the anaerobic zone which means they need to be free-floating and be carried by the water which is difficult with such little flow/water movement going into the DND. So I added the fluidized plastic media and a small circulation pump inside hoping the tumbling action and the flow would suspend the PAOs and they would be carried outside. I thought the anaerobic zone would be safe from the introduction of oxygen even with the flow since the amount of the water going into the DND is very small and the flow inside is diffused by all the media inside.
This is just all in my head and I am aware it is very unlikely to work.
I have no way of knowing if this marine PAOs (bacteria) are in my tank or if they can even be obtained. If anything, my established tank is even less likely to have any PAOs since they would have likely been out-competed by the others already (more established tanks tend to have less biodiversity).
Also, it is very difficult to know or test for it even if it did work.
I don't expect much from it and I just did it because it was easy to do. Just drill a hole on the top lid, cut the 3w USB pump wire, run the wire through the hole, connect back the wire, seal the hole with silicone, fill the top exit part of DND with floadized plastic media and run it like a fluidized filter.
Who knows, I might learn something from this somehow.

Funny that the same exact idea popped up in my head today. Wonder if this modification is working for you? Do you see slimy stuff getting flushed out when the pump is on?

Some carbon sources may perform better at reducing PO4 - KZ Zeostart and TM elim NP might be worth trying. I think both of them has a bit of ammonium inside to facilitate PO4 reduction at low NO3.

My thought was to use this as a bacteria breeding ground to feed SPS and potentially NPS, by using a "nutritious" carbon source like TM Bacto Balance or TM Plus NP. The carbon source would be dosed on a timer and say, 30 minutes before the next dosing, the mixing pump would turn on to release the biofilm on the fluidized media and flush it into the tank. Whatever doesn't get consumed can be removed by the skimmer. The timing may help prevent unconsumed carbon source being flushed into the tank.

Again, this is all in my head as well!

 

[charleydavis]

What I have under the cabinet...

Resun 450 chiller
10G sump (5G max level)
Dymax LS10 skimmer (rated 400L)
3000L return pump
Nitrate destroyer

Not TOTM worth if you ask me but at least it works satisfactorily.

TOTM???

 

[twentyleagues]

TOTM???

That would be nice! Especially as a tribute to Donovan. Unfortunately he passed away quite a while back.

 

[Gtinnel]

TOTM???

Are you asking what TOTM means? If so it’s just an abbreviated for “Tank of the Month”.

 

[charleydavis]

Are you asking what TOTM means? If so it’s just an abbreviated for “Tank of the Month”.

Thanks

 

[twentyleagues]

Thanks

Are you asking what TOTM means? If so it’s just an abbreviated for “Tank of the Month”.

Oh sorry I guess I misunderstood it was a question as to what it meant.

 

[Lil Puff]

Hey guys, I’m having issues where my dnds output flow completely stops then changes to a steady stream randomly. has anyone come across this issue? photo of my dnd for reference.

 

[CNDReef]

Hey guys, I’m having issues where my dnds output flow completely stops then changes to a steady stream randomly. has anyone come across this issue? photo of my dnd for reference.

It’s most likely getting clogged with bacteria, the issue will be finding where. I’d check in reverse order from output in. Might have to change the media size, bacteria being added or the dnd itself might be too small to handle that high of nitrates going in.

 

[blazn]

Hey guys, I’m having issues where my dnds output flow completely stops then changes to a steady stream randomly. has anyone come across this issue? photo of my dnd for reference.

I'd expect that bacteria is impeding the flow in your DND, depending on how long you've had it in operation. I've had my DND in production for coming up on 2 years and it has maintained my NO3 exactly where I want it. But, the output flow had been reducing for the last couple months and I was pretty sure it was due to bacteria growth limiting the water flow. So, yesterday I took the DND out of my sump, separated the tubes from each other and flushed fresh saltwater thru each PVC tube several times, until the water flowed thru each tube freely. The input tube certainly had the most visible bacteria in it and the most that was flushed out. This did improve the output flow of my DND...not to where it was when it was new, but it did improve the flow. So, bacteria growth certainly can impact the flow thru your DND and may require some occasional maintenance in order to keep it functioning correctly.

 

[piranhaman00]

I have never been able to dial mine in, I am constantly adjusting, not a big deal.

 

[Curiousbranching]

Can someone please tell me if I can fill both DND towers with Eheim Substrat (bioball-type) filter media?

 

[blazn]

Can someone please tell me if I can fill both DND towers with Eheim Substrat (bioball-type) filter media?

I am not familiar with Eheim Substrat, but it appears to provide the same benefits as ceramic media and possibly without silica being released into your system, which can increase diatoms. I would expect that it would work fine in a DND.