Denitrification.

[esoxlucius]

years ago I was reading up on Kmuda going through the process of making DIY denitrification system, and eventually he came up with a 7 foot tall PVC tower. His lessons learned about why sometimes it fails are here

Denitrate Tower - "Safe Denitrification"

www.cichlid-forum.com

Thanks for sharing that, totally fascinating. But the complexity of it all just hits home, for me personally anyway, that this type of a project may be a little more than I can chew, without eventually choking. Lol.

People with pothos and the likes need to read that too. The fact it took a full dedicated room of terrestrial plants (far superior than aquatic plants at nitrate reduction), to achieve 0ppm nitrate on just an oscar tank speaks volumes as to the benefits of having a few pothos roots dangling in your overstocked monster tank.

 

[Raka]

I had my pleco tank at 0ppm for a year plus with anubis and duckweed. I do not believe the anubis is doing much to anything as growth is incredibly slow however with duckweed growing through multiplication I have yet to see a plant keep up with it. I was going down this rabbit hole a couple years ago myself but achieved the end goal with a top layer of duckweed and an air stone to keep it out of the HOBs currrent. I was even over 2 weeks no changes and still seeing 0ppm on various tests done at 3 locations, I assumed I was doing it wrong had it confirmed at the LFS and a Petco.

 

[esoxlucius]

I had my pleco tank at 0ppm for a year plus with anubis and duckweed. I do not believe the anubis is doing much to anything as growth is incredibly slow however with duckweed growing through multiplication I have yet to see a plant keep up with it. I was going down this rabbit hole a couple years ago myself but achieved the end goal with a top layer of duckweed and an air stone to keep it out of the HOBs currrent. I was even over 2 weeks no changes and still seeing 0ppm on various tests done at 3 locations, I assumed I was doing it wrong had it confirmed at the LFS and a Petco.

Now I think your set up is right in line with my skill set, lol. If duckweed alone can keep a tank with a pleco in at 0ppm nitrate for over a year, then i'm signed up. I've got a planted 180 and toyed with the idea of duckweed. Two aspects put me off. The fact it would eventually cover the whole tank and block out light for my other submerged plants, and some say once you've put duckweed in your tank you can never get rid of it!

To further cement your claim, did you ever do nitrate tests pre duckweed era so a clear comparison can be established?

And just out of curiosity. We have duckweed in abundance in our local waterways (uk). Will this "coldwater" duckweed be ok in tropical set ups or do hobbyists have to use a different type of duckweed?

 

[Raka]

Yeah tank was getting regular weekly or bi-weekly before, right around the 50% mark each time. Would reach about 20ppms before testing.

It will cover the whole tank but doesnt block much light if it is monitored and maintained. I used to scoop some out each week to prevent it from "piling" up,my sailfin does this for me now at a rate that is quite impressive. Some days I turn the tank on and 60-80% of the duckweed is gone from the surface and converted into massive pleco poops.

They call it aquarium herpes for a reason. But tanks with a lot of surface movement prevent it from establishing. This would leave me to reason that I could remove it that way over time. I haven't tried to get rid of it personally, its nice to have to trade with clubs. lfs will buy it but I usually just donate it to stay in good relations.

 

[BIG-G]

This may be of some interest if you haven’t already seen it
Scroll down a bit there are a few different videos on anoxic filters

Kevin Novak Ph.D.

www.youtube.com

Duckweed will definitely eat up some nitrates, The thing that bugs me about duckweed is it gets every where and if you use HOB filter it can get pushed down by the return water flow and then stuck to the filter Intake clogging it up.
I prefer to use Salvinia it’s less prone to some of the problems duckweed poses and will do the job.

 

[Rass]

I'm with duanes, plants are something I've becoming heavily invested in. I use them anywhere I can and have seen some amazing results in nitrate reduction. If done properly, you can get away with zero nitrates all the time. My guppy tank is nothing special, just a 20 gallon that's planted with aquatic and terrestrial plants. But no matter how long I go between water changes, the nitrates don't even register. Total zero. The only reason I do changes is for minerals for the livebearers.

 

[twentyleagues]

I've been "testing" the Dr Novak biocenosis baskets and so far the results are promising. I need more time to do more testing before I actually say if it truly works or not and if it's a permanent solution to denitrification. I've spent the last year-ish researching and have only actually set up the baskets about 3 months ago. My goal is less waterchanges not 0 waterchanges. Fresh water input is more then denitrification.

 

[esoxlucius]

There's some excellent information in this thread regarding denitrification. Nitrate is undoubtedly the bane of all our lives hobby wise, and hobbyists all over are going to great pains in an attempt to reduce it, with varying degrees of success.

Then I started thinking about it from another angle, completely flip it on its head. What can we do to prevent nitrate from building up in the first place, or to put it another way, prevent it from building up as fast? After all, that would be a far better way of denitrification than attempting to deal with it when it's already built up to unacceptable levels. I was going to start another thread to discuss this but it tags nicely onto this one.

I think the biggest player attributing to nitrate build up by far is the fish themselves. Ok, so you lightly stock your tank with little fish and throw in a load of plants to combat nitrate build up. Yeah, that'd work, to a degree. But here on MFK we have big tanks with big fish, many arguably overstocked, guilty as charged on that one, and not all tanks are planted.

So, what's left to keep nitrates from building up? FEEDING. The biggest factor in nitrate build up by far is how much we feed our fish and the resulting by product. We don't need fry or juveniles in this particular equation, let's just say we have adult max sized fish. We're all familiar with the phrase "feast or famine". We know that fish sometimes have to survive in the wild on very little food, they can go for days without eating. But yet in the home aquarium they're fed every day by most and even multiple times per day by some. Some of us throw in a "fasting" day, but in the overall scheme of things what's a single fasting day per week actually do?

I suppose all this is leading up to a question, and that question is.....realistically could we get away with feeding once or maybe twice per week, even less, in our attempt to reduce nitrates which would inevitably lead to the "stretching out" of water changes, rather than even have the need to go down the route of complex denitrification processes which are above many hobbyists level of understanding. That'd be me, lol.

I don't mean go to the level where you're starving your fish, there'd be a gradual change in appearance if they were undernourished so at least you'd have a visual check if that was the case. I mean, who knows how much food the fish need, there must be studies on it? There'd be health benefits too in regard to fatty liver disease, and probably many more that I've never heard of, you guys tell me.

Pros and cons???

 

[Rocksor]

Here's the thing, there's a feast and a famine period with fish. Generally feasting happens prior and during the growth of fry. As adults, the big fish are more than capable of surviving really long periods, like weeks. So feeding should be based on age as well. Then it boils down to what they eat (based on mouth structure), with some eating more often (eg less nutritious food found in detritus matter) to other fish. We keep thinking that they must eat as often and as much as we do, but they are cold blooded, and the environment they are in are at least 10 degrees cooler than other body temperatures.

From experience, 1 week of not feeding adults produces no change in the API test that I can see between 10-20ppm. Feeding every other day, and no water change a week makes it go to orange-red so more than 20 ppm. In my eyes, feeding habits are one of the biggest contributors to nitrate rising, more so than overstocking.

 

[esoxlucius]

Here's the thing, there's a feast and a famine period with fish. Generally feasting happens prior and during the growth of fry. As adults, the big fish are more than capable of surviving really long periods, like weeks. So feeding should be based on age as well. Then it boils down to what they eat (based on mouth structure), with some eating more often (eg less nutritious food found in detritus matter) to other fish. We keep thinking that they must eat as often and as much as we do, but they are cold blooded, and the environment they are in are at least 10 degrees cooler than other body temperatures.

From experience, 1 week of not feeding adults produces no change in the API test that I can see between 10-20ppm. Feeding every other day, and no water change a week makes it go to orange-red so more than 20 ppm. In my eyes, feeding habits are one of the biggest contributors to nitrate rising, more so than overstocking.

I was going to ask whether anyone has done any meaningful tests regarding different feeding patterns and resulting nitrate accumulation. But to do that very accurately, which would be paramount in this exercise, you'd need an accurate measuring device for testing the nitrate level. And as you've proved, API ain't it. All i've got is the API kit so doing a rigorous exercise on my 360g tank over a period of a few weeks would only supply me with very vague results. Maybe there'd be a pattern in results yes, but to do it right you'd want actual figures.

Target feeding certain fish would also help. As an example, all my fish are max size adults in my 360g except a shoal of filament barbs which are mid size, still growing. I can target feed my filaments easily with small surface flake/pellets. They are lightning fast and clear surface food before the big boys even know it's there.