I would suspect that their lifetime would be many years. The media rings should only be replaced if they are decomposing or are totally blocked and have lost all their ability to house the bacteria that forms as and where they are supposed to. The normal thing to do is to wash about 3/4ths of them well and then only rinse the other 1/4 before putting them back to work in the filter thereby keeping the cycled bacteria alive and working.
There is no "correct time". I would suspect that their lifetime would be many years. The media rings should only be replaced if they are decomposing or are totally blocked and have lost all their ability to house the bacteria that forms as and where they are supposed to. The normal thing to do is to wash about 3/4ths of them well and then only rinse the other 1/4 before putting them back to work in the filter thereby keeping the cycled bacteria alive and working.
That depends on the kind of filter you have. The best filter you can get is a power filter with compartments for different filter media. With one of these you can easily clean out one media at a time thus keeping the cycled bacteria in there. The worst filter of the lot which IMO should never be used, is an undergravel filter because it can not be serviced or cleaned at all. A filter should only be cleaned when the water flow is badly reduced. Only replace some of the media and only rinse loose rubbish off what you keep. The reason for this is to preserve the good Ammonia and Nitrite removing bacteria that have formed in the filter.
It is exactly what you called it. "Slime". You should clean the filter media before this happens. Most successfull keepers of animals (pets) attend to the cleanliness of their charges/pets quarters and conditions very regularly and meticulously. My advice is to strip down and scrub the filter clean, and replace most of the media. Reserve some of the old media keep it wet and rinse it gently. This rinsed "old" media will innocculate the new clean media with the necessary bacteria to cycle the filter. Then service the filter regularly, keep an eye on the water quality in future and replace at least 50% of the water every week.
A media change involves changing out the 'stuff'(media) inside your filter. Changing carbon, fine filter pads, cleaning sponges, and rinsing biological media are all examples of media change in an aquarium.
The denser the media the less airflow through it.
There are many different filter media commercially available. They range from fine fibrous wool type media through activated charcoal which both need to be replaced regularly to the various ceramic noodles and filter sponges that can be rinsed and reused many times. I prefer to use a mixture (layers) of several types of media including all the above in a power filter.
You can either let the tank sit 'fallow' (empty of fish) for about eight weeks or you can remove and boil the gravel, replace all the water and replace or boil all of the filter media and decorations.
its a filter that blows air into the water you can usually get them at your local pet store
Changing the filter media on an Aprilaire 5000 can be an involved process. First, remove the front cover then pull the filter housing out of the air purifier. Second, locate the latches/buttons on all for corners of the housing, depress and lay the end panels down. Third, carefully remove the used media from the housing, it should be setting on a rail/groove on the two longest sides. Fourth, place the new media into housing and open, ensure the cardboard flaps are placed inside the groove to hold the media open in the housing. Close media housing, ensure all four corner latches catch. Re-insert media housing into purifier and replace front cover.
If you have a power filter it should come with the required filter media. Firstly follow the directions on how to position the filter and where to place the media. If the aquarium is a planted one there is no need to do much other than turn it on because the plants will have some good aerobic bacteria that will end up lodged in the filter media where you want it. If the tank is a bare tank you will need to cycle the filter either by adding some old but freshly used filter media or purchasing some filter cycling bacteria at a pet shop. There is another more complicated method using Ammonia but I won't go into that here. If the filter is air as opposed to power driven, you can use whatever filter media is recommended by the pet shop and use the above techniques to cycle it.
Most likely, no. The filter media (paper) inside the oil filter may not be compatible with fuel.
Your filter will tell you on the side of it how much media sand to put in it.