There seems to be a lot of conflicting info online about filter maintenance so I'm hoping to get some good answers here.
1. How often do I have to replace filter media and sponges (this is on a fluval U3)
2. How often should I clean my filter and how.
1) You replace the filter media when it starts to fall apart. The exception to this is carbon (small black granules), which is not normally needed in the average aquarium. If you do want to use carbon in a filter, it should be replaced every couple of weeks, depending on what chemicals/ heavy metals are in the water, and what grade of carbon you use.
Carbon comes in Highly Activated Carbon, Activated Carbon, and normal Carbon. The highly activated is the best, then activated and normal carbon isn't as good as the two previous types.
If you have carbon in a filter, it will remove medications and plant fertilisers you put in the tank.
If you have chemicals/ heavy metals in your water supply, then you can put carbon in the filter to help remove these. Or better still, filter the new water through carbon before using it in the aquarium.
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Some filters have Ammogon/ Zeolite (small white granules) in them. This is used to remove ammonia from the water and is not necessary for most tanks. The beneficial filter bacteria that live in the filter will normally eat the ammonia and convert it into nitrite, and more bacteria eat the nitrite and turn it into nitrate.
If you have Ammogon/ Zeolite in the filter, it removes the ammonia from the water and stops the beneficial filter bacteria developing. This can lead to ammonia levels going up in the tank when the Ammogon/ Zeolite is full, and this in turn harms the fish.
If you have ammonia adsorbing granules in a filter cartridge, cut the cartridge open and tip the contents in the bin. Then put the cartridge back in the filter. Add a sponge to the filter as well and in a couple of months time, you can remove the cartridge and just use the sponge.
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2) I recommend cleaning power filters at least once a month, and every 2 weeks is great. The exception to this is when you are first cycling a filter, then you do not clean it for the first 2 months unless if blocks up and the flow is significantly reduced.
The reason we don't clean new filters is because it takes time for the beneficial filter bacteria to establish a biofilm on the filter media/ materials, and if you wash the media before the bacteria are properly attached, you can get rid of the bacteria and interrupt the cycling process.
If you have an under-gravel filter, they should be cleaned with a gravel cleaner every week when you do a water change. Again, don't clean an under-gravel filter during the cycling process, and wait at least 2 weeks after the filter has cycled before you clean it.
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To clean power filters, turn them off and unplug them from the power socket. Remove the filter from the aquarium and take it apart and wash the filter media in a bucket of tank water. If it's really dirty, wash it in a second bucket of tank water. When it's clean, put the media in the tank or a bucket of clean tank water, and tip the bucket of dirty water on the lawn/ garden.
Wash the filter case out under tap water. Take the motor apart and remove the impellor (magnet with 3 or 4 plastic blades on one end) and impellor shaft. Wash these items under tap water.
Caution when removing and cleaning these parts. Most impellors have a small plastic washer and rubber grommet on each end of the impellor shaft. If these pop off and go down the drain, the impellor assembly and subsequently the motor, will not work properly and you will need to replace the missing piece/s.
Impellor shafts can be steel or ceramic. The ceramic ones don't wear as much but are easy to break so care must be taken when removing and cleaning these pieces.
Wash the inside of the filter's motor, under tap water. Aquarium water pumps and power filters have their electrical components sealed in a plastic resin so water can't get onto them. So do not worry about getting water on electrical parts in the motor, it won't happen.
Once the filter case, motor, impellor assembly, and filter media have been cleaned, reassemble the motor and put the filter back together. Put the filter back on/ in the tank and fill with water (if it's an external filter). Plug the filter into the power socket and turn it on. Check for leaks and to make sure it's working.
*NB* Make sure your hands are dry when removing or plugging the filter into a power socket and turning it on or off.
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The reason I like filters cleaned on a regular basis is because they trap fish poop and this encourages harmful disease organisms (mainly protozoans and bacteria) to grow in the filter and tank. These disease organisms adversely affect the fish and regularly kill fish.
Basically, the filters trap fish poop and all the tank water is filtered through the fish poop. The tank water is full of harmful disease organisms and the fish have to live in this soup of microscopic pathogens. Cleaning the filter, glass, gravel, and changing the tank water regularly, helps keep disease organisms at low levels and lets the fish live in a clean environment where they will be less susceptible to infections and diseases.
