# At what point can a planted tank sustain itself without a filter?



## automatic-hydromatic (Oct 18, 2010)

Hi guys.

I keep hearing that in heavily planted tanks that the ecosystem will pretty much balance itself out, and you wont even need a power filter any more. That would be really nice if I could do that, and just leave the air pump only running to aerate the water.

I've got a 10 gallon setup that has just 4 Dwarf Gouramis in it (yes, they all get along happily, surprisingly, with the occasional lung at each other to keep another fish out of it's "area", lol), but that's all that's in it, so the bioload isn't too bad. It's got a good bit of plants in it; two Amazon Swords, about 7 or 8 small bunches of Argentine Swords, 2 Java Ferns, a Lace Lave Fern, 3 random Aponogetons, and 2 floating bunches of Hornwort.

Right now I'm just using a HOB unit, but I've got a few questions before I make the decision to turn it off.

1) is this only the case on larger thanks, where there's physically more water and the conditions in the tank are not so condensed and concentrated? if so, that's fine, because I plan on upping to at least a 55 gallon soon, so that would be good info to know

2) my substrate is pure gravel; nothing else. does this only work good if the system is set up with a peat-moss and gravel substrate or similar?




Here's some photos of the tank:











































































Thanks!


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## AtRandom (Sep 11, 2010)

1) I think that the larger the system, the easier it is to adjust to change (more dilution). My dad says his nano salt-water tanks are much more needy than his 90 gallon reef tank. Contrary, micro-biosphere globes are almost completely self-sustaining and can live for years before collapse. Tank size should be relative to a plant/fish ratio.
2) Gravel may work in a micro-biosphere, but in a larger aquarium I do believe you will want to use some sort of clay or "soil" that will lock nutrients into the substrate for any rooted plants.

I think that a filter is really useful in that it rapidly moves water over nitrifying bacteria, while trapping particles that would otherwise accumulate in the water. This allows you to feed your fish however much they need to eat, without requiring an exact ratio of live-plant bio mass per fish. Each type of plant removes different amounts of fish toxins, and it would be very difficult to find an exact balance. Are you planning to trim plants, do many water changes, or "gravel vacuum?" Inevitably you will become a chemist! I heavily planted a 20 gallon bucket in a semi-shaded area in my yard and put in some Gambusia. The Gambusia had quite a bit of initial die off, and eventually the survivors began to breed. I have never counted more than 3 babies alive at any given time, and there are maybe 4 adults. They produce minimal waste and feed solely on algae and a LOT of mosquito larvae. Also, the fast growing plants over-took the slower, and they disappeared almost completely. All of these plants are considered "floating" (they do not require rooting into substrate). This has no heater, filter, or aeration.
Here's some sites to glance at, they may not help:
HowStuffWorks "The Closed Aquatic Environment"
JPS - Live Aquarium Plants

_The rest of my post is just random thoughts that have popped into my mind as I pondered this topic, my apologies if it makes no sense or I am rambling._

When I got into planting tanks, the first thought I had was, "Can I just leave the aquarium be with nothing mechanical but lighting?" Now I've realized there are a few realities that make this extremely difficult.
An aquarium is a closed system. This means that what you have in the tank is what you have in the tank - including all things detectable and undetectable by modern science or the naked eye. Think of all the chemicals that impact water quality and the needs of both the fish and the plants. Then look at the transfer of energies taking place..
Fish Waste: (Ammonia/Nitrite/Nitrate)
These may be successfully absorbed by plants and bacteria.
Plant Waste:
As plants absorb these fertilizers, they grow, eventually they will overcrowd each other and inevitable die-off will occur. At this point you now have higher, shading plants taking over. Alternatively, some plants may require more fertilizer than your fish afford, and will begin to die off.

If you feed your fish, but do not trim your plants, you are adding to the system, but not taking anything out. If you feed your fish, but you also trim plants, how would you know exactly how much of any plant to trim without making toxins inflate? 
If you stop feeding your fish, they will produce less waste, which will allow their waste to run the nitrogen cycle before dangerous levels of toxins build up. If your fish ate the plants, that would take care of over crowding plants. Throw some little bugs like daphnia in there to speed up the process of breaking down dead plants/fish poops(?).
Eventually things will shift around: fish are gluttons by nature, just like humans, so they will munch down their favorite (or possibly only) edible plant, fatten up, and poop all over. Now the inedible plants are fertilized by the demise of the edible plant, and your fish require food again. If you continue to not feed them, a few will starve to death while the hardier ones will wait for their food-plant to regain its strength and you have reached an equilibrium - provided that the plant can in fact recover from its losses without the other plants having already overgrown it in the previous time frame.
Also consider evaporated water replacement or any water changes will add algae fertilizers to your tank. If algae starts growing all over everything, you'll need something to eat that algae, or your plants will die!

If left completely alone, I do believe it is very possible to have an equilibrium tank survive for long periods of time, but you will lose quite a bit of your inhabitants and it will turn into a "dirty" looking pond. However, you can add CO2, scrape algae, feed your fish, fertilize, etc. and have a very plant-crowded (single species dominant) aquarium. You could trim these plants, but you will end up asking again, "how much can I trim without effecting the plant biomass per fish ratio?"


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## automatic-hydromatic (Oct 18, 2010)

all good info  thanks

I didn't plan on just completely leaving it alone. I'll still do water changes and top-offs when needed, and trimming the plants would definitely be a must; I'm trimming dead leaves off every week as it is now, and constantly trimming the large Apongeton on the right of the aquarium just because of how fast the stupid thing grows.

I do want to get some small shrimp to put in, to help control the dead plant matter and maybe algae though. the Mollies I use to have use to actually take care of the minimal algae the tank developed. Without them in there, the algae growing on the top of the log getting light is obvious now within a week, lol


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## AtRandom (Sep 11, 2010)

Lol, yeah I dont know why i went off on that long tangent about "what if" stuff. I think a good test for you would be to take your next water change and put your HoB in a separate bucket with it. Then closely monitor your water parameters. The only thing I can see really making a difference is the level of water flow moving the fish pooh over the gravel so your bacterias can go to work. If you try that test, you can always just throw your filter back on the tank from the other bucket and do a water change if needed. Also, make sure you feed that bucket during the experiment just to keep the filter alive. As long as the fish waste isn't stock-piling all over the place and is actually being broken down at a moderate rate, I think it just might work! Good luck, and let us know if it works out so I can copy your setup! *wink
Regards,
Craig
PS - Its a very nice tank by the way, I am diggin' that spacial placement of rock/wood/plant.


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