Filter Cartridge Changing

[Aaron Muth]

I was wandering, how often should I change my filter cartridge. I had a filter cartridge for around 4 weeks and when I switched it about one week ago when I did my water change a my dwarf gourami looks like he is getting fin rot. I also have a white lobster in the tank. I can’t tell which could be the cause of his fin damage.

 

[Byron]

Whitish edges to fins can be caused by fin rot but also (and more often) by poor water conditions or nipping. Here, I would suggest the lobster is the fin issue. Fish and lobsters (or any similar crustacean) should not be housed together.

As for the filter cartridge, there are two things to separate...mechanical filtration (as from carbon or other media within the cartridge) and biological (thee colonization of nitrifying bacteria on any media). The latter never "wears out" but the former will usually become ineffective as chemical filtration depending upon the amount, bioload, water parameters/conditions.

There is no need to replace media that provides biological filtration provided the water is still able to get through and is not being blocked, nor the opposite being able to get around the media. So rinsing this media regularly to keep it clean is all you need.

Chemical filtration as I said depends upon thee chemical. Carbon for example will become full as it adsorbs (it is adsorb, not absorb) substances and no longer be effective as chemical filtration. It will still function as biological filtration, any media will. Whether or not you need chemical filtration is debated by many, or may be necessary for specific issues your water may have.

 

[Aaron Muth]

Whitish edges to fins can be caused by fin rot but also (and more often) by poor water conditions or nipping. Here, I would suggest the lobster is the fin issue. Fish and lobsters (or any similar crustacean) should not be housed together.

As for the filter cartridge, there are two things to separate...mechanical filtration (as from carbon or other media within the cartridge) and biological (thee colonization of nitrifying bacteria on any media). The latter never "wears out" but the former will usually become ineffective as chemical filtration depending upon the amount, bioload, water parameters/conditions.

There is no need to replace media that provides biological filtration provided the water is still able to get through and is not being blocked, nor the opposite being able to get around the media. So rinsing this media regularly to keep it clean is all you need.

Chemical filtration as I said depends upon thee chemical. Carbon for example will become full as it adsorbs (it is adsorb, not absorb) substances and no longer be effective as chemical filtration. It will still function as biological filtration, any media will. Whether or not you need chemical filtration is debated by many, or may be necessary for specific issues your water may have.

That’s the gourami.

 

[Byron]

That’s the gourami.

Yes, I said I would think the lobster is the cause of the gourami's fin issue. But it could also be stress from the other factors I mentioned previously. Or a combination.

 

[Colin_T]

Check the water quality for ammonia, nitrite, nitrate & pH?
If you have any ammonia or nitrite, or a nitrate reading above 20ppm, then do a 75% water change and gravel clean the substrate each day until the levels are back to 0.

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As Byron mentioned, you don't need to replace filter materials unless you are using carbon (black granules) or an ammonia adsorbing granule (damn you Byron, word of the day "adsorb" ).
If you have black or white granules you can make a small cut in the filter pad and throw the granules away, then squeeze the filter pad out in a bucket of tank water and re-use it. You do not need carbon or ammonia adsorbing granules in an aquarium unless you have chemicals or heavy metals in the water. if you have chemicals or heavy metals you can use carbon, otherwise save your money and leave it out.

If you add a couple of sponges to your filter (from another brand of power filter), it will increase the filtration area and if you have to replace the filter pads (because they are falling apart), the sponges will house some filter bacteria that will help keep the water clean. You can also get cylindrical sponges from an internal power filter and these can go over the intake strainer of most external filters and provide additional filtration media. Filter sponges can be squeezed out in a bucket of tank water every couple of weeks and will last for years.

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re: the damage to the gourami's fins. It looks like physical damage, probably caused by the crayfish. Crayfish are nocturnal scavengers that should not be kept with fish because they will catch and eat fish when the fish are asleep at night. Move the crayfish into its own tank asap. If it's going to be a while before you move the crayfish, make sure you feed it at night before lights out and it will be less likely to eat the other fish.