Unless they are so badly clogged up with debris and are stopping the water flow, you should leave them alone. If they are clogged you can clean them, you never replace them with new ones unless they are smashed or decomposing. It is OK to take them out and give them a gentle rinse in warm (not hot) water (NO SOAPS or DETERGENTS) but be carefull not to remove all of the bacteria that are on them. Those Bacteria are the things that people are refering to when they say a "cycled filter" the term "cycled" means the filter has the specialised bacteria that actually do all the major work the filter does ie changing (deadly poisonous) Ammonia into (poisonous) Nitrite and then changing the nitrite into (harmless) Nitrate.
Your tank filter should be changed every month. If your filter becomes clogged, it should be changed right away.
It is best that all fish have a filter besides Betta fish. Betta fish don't need filters cause the filter pushes them over with their big fins. Goldfish should have a filter on there tank because they are often overfed. If you have a filter you won't have to change the water as often. The only fish that shouldn't have a filer in captivity are Betta fish.
When its dirty you need to change the filter.
Fish tank filters are not too expensive to keep using. Most of the money goes towards the initial cost of all equipment. You will probably spend about $20 a year on fish filters if you change them as often as you should. P.S., change the filter once a month.
Generally a filter on a fish tank needs to be replaced once a week. If the fish tank is especially dirty, then it may need to be replaced more often than that. Generally, the more fish there are in the fish tank, the more often the filter will need to be replaced.
Filter a fish? Do you mean filtering a fish's tank? Well you have to filter any fish's tank.
In theory, fortnightly.
they ate fish for food and had sex
no filter because for smaller fish it can hurt or even kill them and for the old filter use bigger fish
YOu can purchase a filter for the tank. Also you might have too many fish in your tank. But every twwo weeks is not very often, most people change theirs once a week.
a fish filter cleans the water and a pump pushes it through a fish filter cleans the water and a pump pushes it through
Fish oil should not cause a change in the color of your bowels. It may affect how often you go to the bathroom.