Hi, bolivian_d
Do you have enough ambient light to keep plants?
Is your other tank near enough, and is the light/canopy suitable for interchangeable use on both tanks?
Even if the sizes aren't the same, if near enough to balance safely on top, or if it's possible to rig a way to do so, (and height above water level reduces too-bright light as well,) that can work, although many name-brand tanks do have built in systems so that such jury-rigging isn't possible.
I have tanks sharing canopy lights - and it's enough to keep plants alive.
I have a (non-Walstad) 10 gallon betta tank sitting on a board across the tops of 2 sturdy wooden bedside tables, with my bedside lamp providing enough light to keep a half-dozen or so Water Wisteria and 4-Leafed Clover alive, albeit together with ambient and some degree of daylight.
That's also one of several tanks having box filters running off a single shared pump.
May not look very nice, but it does the job well enough.
Your entire tank - filter or no - can act as a bio-filtration system, and plants help with --- everything.
http
/www.aquariumfish.com/aquariumfish/d...788&search=
... Probably the biggest repository of helpful bacteria in your aquarium occurs on the surface of each piece of gravel. Each grain, though appearing smooth to the eye, is rough at a microscopic level, and thus provides a huge surface area for the growth of helpful bacteria. So, it follows that if you sterilize your gravel, you will destroy most of the biofiltration in your tank. Not knowing this, hobbyists sometimes remove the gravel for cleaning and have been known to boil it, scald it or (worst of all) use bleach or soap to sterilize the gravel. This is a huge mistake! It kills off the nitrifying bacteria and will allow ammonia levels to increase rapidly in the water. Gravel should never be cleaned with anything but plain, aquarium-temperature water. ...
... Safely Maintaining Filters
The most significant part of your aquarium maintenance is likely to involve the cleaning of one or more filters. Filters don’t remove waste — they just collect it. Nitrifying bacteria grow on every solid surface in the tank, including gravel, glass, plants, decorations and filter media. Indeed, most filters contain some type of biomedia designed to provide plenty of surface area for the growth of helpful bacteria. So, it’s best to take steps to preserve the bacteria on this media when possible.
http/ezinearticles.com/?Nitrogen-Cycle-A...s&id=328078
... Ammonia (NH4) is assimilated in more than one way. Plants (such as Hornwort) and algae can assimilate ammonia and ammonium directly for the biosynthesis. The remaining bulk of decomposed byproducts are utilized by bacteria in a process called nitrification. Ammonia does not last long in a healthy aquarium environment, fortunately. Nitrifying bacteria such as Nitrosomonas quickly break down ammonia into less toxic Nitrite (NO2). During this process, specific species of nitrifying bacteria strip the ammonium of its hydrogen molecules as an energy source. Oxygen molecules are then affixed to the stripped nitrogen, forming the oxide nitrite (NO2).
Another group of bacteria (Nitrobacter ) utilize the enzyme nitrite oxidase that is then responsible for converting nitrite into nitrate (NO3). This nitrate can either be used by plants as a nutrient source, or can be further broken down into nitrogen gas (N2) through the activity of anaerobic bacteria such as Pseudomonas . ...
http/www.malloftheworld.com/aquarium/par...tm#Introduction
... Comparing a plant to a plastic filter, mechanically, the filter wins the contest because plants can't remove any waste from the aquarium. They can, however, convert much of this waste to plant food.
Most experts would agree that biological filtering (using aerobic bacteria) is the most important means of maintaining water quality in the fish tank. The biological filter requires that the toxins produced by fish waste and excess food be broken down in stages via the nitrogen cycle. For new hobbyists, this means that different types of bacteria must break down deadly ammonia (or ammonium) produced in the decay of the waste, to a slightly less toxic nitrite and finally the least toxic nitrate. Plants use the same bacteria system. The roots and base of a plant are loaded with good guy bacteria and, in fact, plants are often used to start (seed) new aquariums. But, plants have other benefits not found in filters. Plants love ammonia and consume large quantities with no need to wait for it to be broken down by bacteria. Typical biological filters can't break down waste beyond nitrates, so this last by-product tends to accumulate and can become deadly at high levels. Plants, under certain conditions can consume nitrates. Many aquariums also have problems with excess phosphate that filters can't remove. Plants can, and do, remove substantial amounts of phosphate from the water.
Aesthetically, plants certainly look a whole lot better than any filter design I have seen to date. In retrospect, I guess it's not so surprising; after all, Mother Nature has had millions of years to perfect her methods. Plastic filters have not even been around a century. ...
http/www.aquabotanic.com/plants_and_biol..._filtration.htm
PLANTS and BIOLOGICAL FILTRATION
by Diana Walstad
http/www.sciencedirect.com/science?_ob=A...9037fe2c1a76d0b
Abstract
Aquatic plants are quite effective in separating metals from polluted waters. A promising method using aquatic plants to sorb metals from secondary treated municipal wastewater is examined in the study. Traditional sewage treatment plants with secondary treatment facilities are not able to remove heavy metals efficiently from the wastewater. In Varanasi, the sewage is mixed with industrial effluents containing high concentrations of heavy metals such as Cr (1.2), Cd (0.09), Cu (0.11), Zn (0.92), Fe (1.8) and Ni (0.07) mg L−1. Eichhornia crassipes, Pistia stratiotes, Lemna minor, Azolla pinnata, and Spirodela polyrhiza were tested for their heavy metal removal capacity from the secondary treated municipal wastewater. Accumulation of heavy metal was higher in roots as compared to leaves. The preferential sequence of percent removal by the selected aquatic macrophytes was Fe > Cr > Cu > Cd > Zn > Ni. Statistical analysis revealed a positive and significant correlation between percent removal of heavy metals from the wastewater and increase in the plant tissues.
You might want to try packing in as many fast-growing plants as you reasonably can and adding a wee dash of Flourish or other fert. as required.
If light levels are low, slow-growing is better than nothing - by a long shot.
It'll make all the difference in your fish's world.
