Why do I need current in a filterless tank?

[Ms.Bubbles]

I am seriously considering starting up a filterless, heavily planted tank (with very low fish load). I've read that going without a filter is possible, but that it's essential to have current in the tank, so at least an airpump is necessary (but I don't want even this).

Why is water current so essential in a (planted) tank? I've heard of many people keeping bettas in a planted, non-filtered tank, non-airpump tank, and they simply changed water every few days or once a week. Why is it possible to go without an airpump in this situation, and not the other???

 

[Watcher74]

Well from what I have read there is an area of undisturbed layer of water around aquatic plants that is much thicker than undisturbed layer of air around terrestrial plants. In a no current situation, it is much more difficult for the plants to pull out any CO2 or nutrients from the water due to that area of undisturbed water surrounding it.

With current or circulation of the water, that undisturbed layer is greatly thinned out, making CO2 and nutrients much easier to reach by the plant.

It also helps to prevent stagnatation of the water. But if you want to breed mosquitoes then keep all current out of your tank.

 

[Riso-chan]

You should at least have an airstone in there, otherwise your fish choices will be limited to bettas and related species. Also as Watcher was saying, your plants will even need some sort of current to thrive.

 

[dr_sudz]

You need some sort of water movement to allow for gas exchange. Plants will produce O2 through out the day while the lights are on, but once the lights go out the plants need to turn nitrates into plant food and thus produce CO2 while the lights are out. Heavy planted tank will not be able to keep your fish alive.

 

[misopeenut]

you really dont need anything...
if you can do water changes then youre fine, if not get plants taht photosynthesize a lot.

the picture above shows 2 filterless tank, one has heater but, no air stone.
she just adds water every week...
that tank has been running for about 2 month now... so you dont really need current, maybe you might get some oil layer thing on the surface but taht can be solved by the water changes
:thm: good luck

 

[Roan Art]

This would actually be a good question for the Plants Forum. I know RTR has several veggie filter tanks.

Post a copy of this in there and see what the gurus say.

Roan

 

[joephys]

You don't need current during the day, the plants will produce oxygen and the tank should be fine. At night though, there could be very little gas exchange and your plants and fish could use up all the oxygen. Running an airstone at night will help keep O2 levels safe for your fish. That is the main reason.

 

[TKOS]

Bettas can breathe air at the surface. They are suited to filterless tanks.

 

[RTR]

IMHO & IME, plants always need current. The boundary layer effect which Watcher mentioned is your enemy. Even Diana Walstad uses strong current in her filterless tanks.

Certainly you can have plants in a filterless and currentless tanks, just as you can keep bettas and goldfish in bowls. Should you though? I think not.

All my veggie/plant filters have stronger current than the tanks that they are coupled with - for one simple reason - to make the the plants grow better - by disrupting the boundary layer, by delivery of nutrients to the plants, and for dispersing the oxygen from the plants through the water column so that it can be carried back to the maon tank along with the cleaner water.

 

[Ms.Bubbles]

Hmmm, it looks like misopeenut has a few (nice!) non-betta tanks without filters or airpumps

miso, I wonder how much water is necessary to change out in these tanks per week? Also, you say "get plants that photosynthesize a lot"--what type of plants would that be? Looks like a lot of anacharis in the tank at the right...