Your experience with live plants alone keeping a tank clean?

[MultipleTankSyndrome]

Asking because I have 25 pothos trimmings rooting in my tank, which when they do root are obviously going to remove a ton of NH3. NO2, and NO3.
Not going to skimp in the slightest on the water replacements or filter maintenance, but I'm wondering whether doing those things is going to end up being solely for the sake of giving fresh water, replenishing trace minerals, and providing mechanical filtration because the pothos remove all the nitrogenous compounds already.
So I'm wondering what others' experience is with how many nitrogenous compounds this amount of planting removes.

 

[Krismo962]

It's very overated imo,you would need quite alot of pothos to remove a significant amount of nitrates.
I don't have any mechanical filtration in this tank,just plants. It does have a sponge filter in it but it hasn't been running for a long time. 40g, only filled about 8-10 inches 8" snakehead lives in this tank it doesn't like current anyway.

No water change for 8 weeks now.
View attachment 1469733

View attachment 1469734

View attachment 1469735

 

[MultipleTankSyndrome]

Interesting. I know of one report which seems to have kept the NO3 very minimal even with no water replacement: https://www.aquariumadvice.com/forums/f20/attempt-at-nitrate-reducing-pothos-filter-328601.html
The ratio of fish stocking (I assumed pet store sizes for AqAdvisor) to tank size to number of pothos plants (that looks like either 2 or 3) suggested I would need about 25 plants for my tank. And that account reports its success with only a young, small pothos, whereas an older and larger one (which those small trimmings will eventually grow into) would remove considerably more of the NO3.

Also, I do wonder whether the fact that you had a ton of aquatic non-pothos plants may have affected your experience compared to someone who was only using the pothos? Apparently pothos absorbs NO3 much faster than aquatic plants so there could have been quite a bit of leftover NO3 for that relatively small amount of pothos you had.

Having said all of this, I will keep a close watch on the NO3 as soon as the pothos takes root to see just how much is removed. I'm taking what you said as an indicator of pothos experience possibly being quite variable from tank to tank.

 

[FJB]

Removal of nitrogenous compounds is but one of the many reasons why water changes are needed. That would be in a tank that also hosts a fish community.

 

[eon aquatics]

i recently set up a 20 gallon im planning on keeping it with live plants/waterchanges/siphoning and no filter

 

[Fishman Dave]

The amount of nutrients the plants take out of the water will of course to some extent depend up the size of the tank, the number and size of fish you have and the amount you feed them, hence the amount of nitrogenous waste you add to the tank.
Some of our peers have had excellent results keeping nitrate levels at or just above zero, but that appears to be in low stocked tanks of large volume with as large a dedicated tank volume housing plants in full sun lighting all year round.
Trying to replicate this for example, where I am in the uk, would just not be practical due to the cost and amount of lighting I would require to grow 25 terrestrial pothos in a 4ft tank of their own with roots in water as a filter for another low stocked 4ft tank.
Instead I could have two 4ft display tanks both with mechanical and biological filtration and regular water changes and keep three or four times as many fish.

 

[MultipleTankSyndrome]

Come to think of it, I'll keep this thread updated as the pothos root, while still doing the water replacements and filter maintenance as usual (as I said before). Others could find that useful if they choose to use plants to help their filters and water replacements out.

 

[duanes]

My 300 gal system (180 main tank/125 sump/refugium) maintains a nitrate level below 5ppm.
The main tank is bout 40% covered in terrestrial plants like daefenbacia, pothos and a few others,

Above the surface, the shot above, terrestrial roots grow down 20 inched into the tank below.

I find pothos and other roots often collect detritus, which can be easily jarred off into dust clouds, its why mechanical filtration is used.

The fish load in the tank is 5 cichlids (5"-7") two 4" tetras , and an 8"pleco.
The sump is next to the tank, and slightly lower (shot below) , it is heavily planted with Vallisneria, and has a population of about 50 one to 3" shrimp, which help break down detritus, and are sometimes fed to the fish, as they overpopulate.



There is a 20" x 21" x2" matten Porret filter pad in the sump behind where the 1500gph pump sits, it is used for mechanical filtration , and there a few bags of ceramic biomedia, and porous block.

I try to maintain an every other day 30%-40% water change schedule, which along with the heavy planting, and this seems to meet my nitrate goal of < 5ppm.
Nitrate has been this level for for about 3 years.

Beyond just acting as a nitrate sponge, the aquatic plants also help oxygenate during intense light periods (and to me there's oodles of aesthetic appeal) .

 

[MultipleTankSyndrome]

That's a fantastic setup you have there. I agree with you on the aesthetic appeal part, looks a lot like a tropical jungle understory or similar.

What you said about how much of the tank is covered and just how deep the roots are could be a good guide if the 25 pothos don't quite fulfill it.

 

[MultipleTankSyndrome]

Despite all my progress I completely forgot to update here. It's been a while.

Most of the 25 clippings failed to root for some unknown reason, but some did. How these are doing is as described below.

I decided to move this rooted pothos to the 110 liter because its roots kept getting destroyed whenever I cleaned the 473 liter with tri-weekly 55% water replacements (which, go figure, are already keeping the NO3 of that tank very close to undetectable with API. It's as if they told the pothos it wasn't needed by destroying its roots, lol).

Since then, although the leaves are nothing to write home about, the roots are doing quite well. They have grown very long in a not-so-long timeframe, leading me to believe plenty of NO3 has been sucked up by the pothos.




Accompanying them as other houseplants go is a spider plant, whose roots also couldn't withstand the 473 liter's cleanings. But as you can see in the above picture, said roots (on right) are doing well in the 110 liter.

And of course, accompanying them both is my massive clump of floating hornwort clippings.



I don't know the exact ratio of plant to fish mass, but the API test kit tells me there are enough plants to eat up the nitrogenous wastes as soon as they are produced and keep them undetectable at all times.
This remained the case when I removed the sponge filter to serve the dwarf chain loaches in my quarantine tank (or in other words, the plants kept the tank cycled with 0 nitrifying bacteria). I am hoping that the plants can still handle 100% of the bioload when said loaches are transferred to the 110 liter, but if not, more pothos/spider plants/hornwort are to be added.

One final plus is that the way the 110 liter is set up allows for water replacements that don't destroy plant roots. I can simply drain out the appropriate amount of water with a siphon and dump new water in while leaving the plants unharmed.