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Help me build the ultimate nitrate-sucking setup


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So...I have an idea...

I recently adopted/inherited a very large Central American cichlid. You can read more about him here if you would like. Long story short, he'll pretty much destroy anything you put in the tank with him, be it flora or fauna. He also eats a lot and produces a lot of waste. Consequently, the nitrate levels in his tank stay pretty high. His previous owner was doing 75% water changes every three days to combat nitrates. If I need to do that, I will, but honestly, I would like to avoid it. I think there's a smarter way to handle it.

Obviously, I can't put plants in his tank because they'll get eaten or uprooted. So, my thought was to build a kind of sump system with a spare 20 gallon, put it next to it and just stuff that 20 gallon with plants. I've found promising-looking plans for an overflow that doesn't involve drilling and I figure I can just add a spare powerhead to pump water out of the sump back into the tank, so the engineering of it is not the problem. I'm wondering how I get the most "bang for my buck" plant-wise.

I've got some pothos I can root in there and various stem plants (water wisteria, ludwigia, rotalla, bacopa), but they don't seem great at really sucking up nitrates. I've heard Amazon frog bit is really good, but as near as I can tell, Oregon classifies it as a noxious weed (for good reason), and no one who knows what they're doing will ship it here. I've heard hornwort is also good, but my normal plant sources don't have it in stock. Bamboo could also be an option, apparently. I'd like to avoid duckweed for obvious reasons, but if it's amazing at sucking up nitrates, I guess I could give it a go. What plants would anyone recommend?

And what of lighting? I have no shortage of various aquarium lights, including a few Fluval Nanos. Do I just blast that sump tank with light all day? If algae takes over in that tank, is there a risk of it spreading to the main tank? I don't mind the small tank having algae, but I'd like to keep it out of the main tank if possible.

What are peoples' thoughts here? How can I work smarter not harder?

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Per Father Fish videos the key to nitrate is anaerobic bacteria , this is like the aerobic bacteria that converts ammonia to nitrogen , anaerobic bacteria converts nitrogen to a nitrogen gas allowing it to escape the water.  Anaerobic bacteria require an place to live that is O2 deficient.  I do this in my tank with a deep sub straight.   He recommends at least 3" of sand.  This will allow anaerobic bacteria a place to grow.  

So this might provide a piece of your puzzle. 

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Maybe go for a floating plant for your sump that isn't as much of a pain as duckweed, but still grows crazy fast. I clear out about half of the salvinia from my tank once a week and it's super easy and quick to remove. It grows extremely fast and dense though, so I know it's stripping nitrates out like crazy. Otherwise yeah, stuff that tank with hornwort and go to town. I like the idea of pothos as well, since you could just stick a stem in and have the rest of the plant trail outside of the tank. I love this idea and can't wait to see what you come up with. 

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On 8/2/2021 at 5:47 PM, B1gJ4k3 said:

@GuppysnailI've got a couple pothos plants in an spare AquaClear 110 on the back right now. The don't seem to be doing much yet, but I'm thinking it might not be a bad idea to add some light above them. The tank is in my garage, so it doesn't get a huge amount of sunlight.

A light should help. Mine grow like mad. I cut the roots and stems all the time but mine get tons of light. I have run across hose and sink filters that are inexpensive screw on to remove nitrates but they also remove calcium magnesium and minerals so I never got them. I am uncomfortable messing with the chemistry stuff

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I recommend looking into an anoxic (low oxigen) filtration system. Dr. Kevin Novak (a genuine scientist, not just a hobbyist) discovered this way of filtration for ponds decades ago, and supposedly it also works great in aquaria. He has a very interesting, yet often technical, Youtube channel where explains how to set one up and the science behind it. Why this system isn't discussed more is beyond me.

In my new tank (and in a few rescapes) I will implement this system myself by using a plenum, and maybe a BCB in a filter. The benefit is that it is really cheap to set up and is pretty much no maintenance. It also works if you have fish that eat plants.

I would avoid creating anaerobic environments at all costs, since those bacteria create toxic waste products.

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On 8/2/2021 at 3:43 PM, B1gJ4k3 said:

I'm wondering how I get the most "bang for my buck" plant-wise.

So, I've been thinking a lot about this.  I have a decent sized tank I am putting together for African Rift Lake cichlids, and because I can't really do plants, I want to have a refigium in the sump.  The same question struck me - which one would be the best choice?

My first thought was Salvinia.  It's uses to pull N out of effluent in some counties, and it has access to atmospheric CO2.  But, in reading through some of the scientific literature, it doesn't seem all that great when compared with other submerged plants, probably because it doesn't pull from as much of the water column.

Then, I started thinking about submerged plants.  But my searches of the primary literature were not highly successful.  As with much of this hobby, there isn't really funding out there for direct research and so things like aquaponics research has to suffice.  Well, I can tell you how lettuce does, but that's not a big help for most. 

A few months ago, Fishman posted a video series on YouTube about using what he called "bog filters".  He found that Java moss, but not hornwort, was good at taking up ammonium.  I realize this is not nitrate, but it did get me thinking.  I am planning to run some experiments with ammonium and nitrate to see which plants draw each down most rapidly. 

But initial stuff is looking like anacharis, water wisteria, java moss, and Myriophyllum.  I need to do more testing though.  Right now I want something that can grow without being rooted.  Rooted, there is data that Val is decent. 

Without opening up a whole thing, one thing I will not be considering is trying to cultivate denitrifying bacteria as a means to get rid of N from the tank. 

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getting the right anoxic setup sounds like a real headache.  My money is on floaters and hornwort. 

 

You could even go wild and put a light on top and on the side so the hornwort doesn't get light blocked. 

 

IDK the effect of growing algae in the sump on the tank but if you're worried you could run the return through UV.

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@B1gJ4k3 Here’s what I did (first pic and see the “75 Gallon” link in my sig) I would not try the swords or Vals for Casper, he’s bigger than my Jacks which are a measly 8” and 10”.  But I have bamboo in the tank (totally stole the idea from @dasaltemelosguy picture of his tank.  Also stole one of @dasaltemelosguy picture (second pic) to keep me inspired.

You MIGHT be able to grow Crinums in another tank (in a very deep pot deeply layered with pebbles), then once well established, move them to Casper’s tank.

I also have pothos growing in the shower caddies that steady the bamboo at the top) and in the HOB’s, plus Spathiphyllum growing in the HOB’s.

 

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Ok so I once went down a bit of a rabbit hole reading into using plants for filtration, learning (and since mostly forgetting) about accumulators and hyperaccumulators etc and compiled a list of plants that according to some study or another are good for filtration and that I thought could work in a sump/bog filter set up.

There were many more (think they are listed on Wikipedia?) and it literally lists which plants are good at taking up which contaminants etc and I tried to list the ones that came up repeatedly as good at sucking out multiple contaminants out of water (a lot of the studies are also about filtering contaminated soil too). 

I don't remember all the science stuff but anyway the list I jotted down were:

Pothos
Peace lily
Sedge
Papyrus
Bulrushes
Rushes
Water hyacinth
Bacopa
Mangrove
Water mint
Vallisneria
Cabomba
Dwarf water lily
Duck weed
Willow
Brassica juncea

 

Now my simple list doesn't go into which are grown submerged/floating/emersed/aquaponics etc but I'm sure you can work it out. Might be a good starting point of options to look into? My idea was the right mix could filter nitrates but also heavy metals, bacteria etc etc. It was an interesting rabbit hole at the time honest! 

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The anoxic approach is certainly interesting, but probably not something I'll attempt on this tank. I'm fostering him until the previous owner is able to establish a more permanent living situation so having a first time anoxic setup go horribly wrong and potentially kill his fish is not something I think he'd appreciate. Maybe I'll give it a try in one of my other setups at some point, though.

I think I'll attempt some hornwort and some floaters with the pothos I've already got to see how things go initially. Maybe some bamboo in there as well, just because I like the look of it.

I'll report back with how it goes. In the meantime, does anyone have any recommendations for plants other than Aquarium Co-Op? The don't ever seem to stock any floaters and I could swear I've seen hornwort on there at some point, but they don't seem to sell it anymore. I've ordered from Buce Plant with mixed results before, but they're out of stock on hornwort at the moment, too. Anywhere else that people have had good luck with?

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On 8/3/2021 at 4:44 AM, KentFishFanUK said:

Ok so I once went down a bit of a rabbit hole reading into using plants for filtration, learning (and since mostly forgetting) about accumulators and hyperaccumulators etc and compiled a list of plants that according to some study or another are good for filtration and that I thought could work in a sump/bog filter set up.

There were many more (think they are listed on Wikipedia?) and it literally lists which plants are good at taking up which contaminants etc and I tried to list the ones that came up repeatedly as good at sucking out multiple contaminants out of water (a lot of the studies are also about filtering contaminated soil too). 

I don't remember all the science stuff but anyway the list I jotted down were:

Pothos
Peace lily
Sedge
Papyrus
Bulrushes
Rushes
Water hyacinth
Bacopa
Mangrove
Water mint
Vallisneria
Cabomba
Dwarf water lily
Duck weed
Willow
Brassica juncea

 

Now my simple list doesn't go into which are grown submerged/floating/emersed/aquaponics etc but I'm sure you can work it out. Might be a good starting point of options to look into? My idea was the right mix could filter nitrates but also heavy metals, bacteria etc etc. It was an interesting rabbit hole at the time honest! 

Was just about to post something similar, then I saw your post😄. Thanks, you saved me some typing!

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My list would've been pretty much identical but would have included:

Red root floaters,

Amazon frogbit,

Baby Tears,

Pearlweed,

and much like the Peace lily, Flamingo flower plant Anthurium scherzerianum from Central and South America,

A friend has a 200 gallon tank with lots of Pothos, Peace lily, and Flamingo flower plant mounted on the backwall with their roots by means of rubber twist ties. None of those would be an option in my house though because all of them are highly toxic to cats. However for those without professional feline supervision, here is a link describing the Flamingo flower plant:

https://www.houseplantsexpert.com/flamingo-flower.html

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On 8/3/2021 at 10:54 AM, B1gJ4k3 said:

@eatyourpeas I suppose I could ask them. I love them, but if there's one thing they're not great at, it's plants, unfortunately.

I have luck with the buy and sell groups where people list things. plants like frogbit (nutrients hog) on the internet. If I find a seller closer to me they do better because of similar water conditions. 

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