Do the bacteria present in the aquarium enough to deal with ammonia?

Bacteria in fish tank ?
Bacteria is normal . breaks down ammonia from fish into nitrate.
Nitrate is harmful and requires a water change unless you pump the water through plants google aquaponics.
Algae in fish tank ? buy water snails put in tank

Yes, if there is no gravel in your aquarium, there are not bacteria colonies because they can only thrive in gravel environment, therefor you need to replace the water more often.

The gravel provides a home for beneficial bacteria which help dispose waste products in your aquarium, and the useful colonies of bacteria can only thrive in gravel.

Here are a few brands of chemical filtration that you may want to look into -

http://www.filtersfast.com/P-Fluval-Ammonia-Remover-2800-grams-98oz-Kit.asp

http://www.filtersfast.com/P-AquaClear-70-Ammonia-Remover-Kit.asp

Aquarium filters are a necessary part of operating an aquarium. The fish are confined to a much smaller quantity of water in comparison to their natural habitat. Unlike in open waters, fish waste in the aquarium can quickly build up and increase toxic levels. Fish waste will in turn release ammonia which will kill your fish.

Wet/dry filters work on the principle that the beneficial colonies of ammonia neutralizing bacteria grow best in the presence of well oxygenated water. Wet/dry filters provide a very large air/water surface area and are also adequate for saltwater aquariums.

In sponge filters water is forced through porous foam. Water flowing though the sponge allows the growth of a colony of beneficial bacteria which neutralizes toxic ammonia. Most sponge filters uses two sponges attached to one lift tube which is an advantage that the sponges can be cleaned one at a time, reducing bacterial loss.

Biological filtration is the term for fostering ammonia-neutralizing bacteria growth. There are several that can break down ammonia into less toxic compounds like nitrite and nitrate therefore making your aquarium less dangerous for your fish.

The first thing you'll need to do is to test your water. Water quality is the most important thing in keeping your fish alive and healthy your aquarium water clear if the ammonia and nitrite levels are above zero. You should also check if all aquarium filters and the heater are working correctly. Good luck.

A filter maintains a natural environment that for fish thatbalances the good and bad bacteria in the tank. Additionally, a filter can remove toxins, chemicals and other unwantedmaterials from the water. The filterworks by taking water in from the tank and returning it clean.A pump is just a pump. It pumps air into the tank and creates bubbles, and sometimes a current. It does not clean the tank or balance thebacteria and PH like a filter does.