How often do I really need to change out filter media?

[LisaRose]

So I have the fluval 30 gallon filter for my 20 gallon tank. In the instructions it says I should change out the carbon filter once a month, the mechanical sponge filter once every 2 months, and the bio filter once every 3 months. My tank has been established for about 6 months. To be honest, I haven't changed out my bio filter at all, but I have changed the carbon and sponge filters a few times.

Any advice on how frequently I should be changing out the filters?

 

[FishGirl115]

No not change the biofilter. That what houses all your beneficial bacteria. Always keep that, but clean it once every 3-6 months by squeezing it in a bucket of dechlorinated water.

 

[Demeter]

I very rarely change the media. There isn’t much point to changing it as you’d be removing the bacterial colonies that break down the fish wastes.

I use mainly filter floss, rinsing it every so often duing water changes. Some tanks are more messy than others and they need to be rinsed every water change. When the floss gets all knotted and not so fluffy I will replace a portion of it, never all of it.

As for sponges, I have yet to replace any but there is one or two that are starting to really degrade and could be replaced.

For your cartridges, replace them when they start falling apart. It is a good idea to stuff the new media in with the old media for a few weeks so the new one can get a bacteria colony going.

 

[YellowGuppy]

In a word, NEVER!

In actuality, they should be rinsed as needed (every couple of weeks or monthly) in old tank water. If stuff is really falling apart it can and should be replaced, but certainly not every month or two. Perhaps every decade or two!

Those recommendations in your filter instructions are suited to continued sale of filter media, not the well-being of your stock, filter, or wallet.

 

[LisaRose]

In a word, NEVER!

In actuality, they should be rinsed as needed (every couple of weeks or monthly) in old tank water. If stuff is really falling apart it can and should be replaced, but certainly not every month or two. Perhaps every decade or two!

Those recommendations in your filter instructions are suited to continued sale of filter media, not the well-being of your stock, filter, or wallet.

Good point! Changing out the media that frequently seems unnecessary, only a ploy to keep me buying their products.

 

[AvalancheDave]

Those disposable cartridges make one conflate cleaning and replacement.

I'm forced to clean my mechanical filtration every few days because it clogs then the water levels drop and the pump runs dry.

There is scientific evidence that prolonged filter cleaning intervals can lead to significantly reduced growth rates. And we're talking days not the months that some people go between cleaning their canister filters...

I haven't had the time to do more research but it may very well be that cleaning filters is more important than water changes.

 

[LisaRose]

I very rarely change the media. There isn’t much point to changing it as you’d be removing the bacterial colonies that break down the fish wastes.

I use mainly filter floss, rinsing it every so often duing water changes. Some tanks are more messy than others and they need to be rinsed every water change. When the floss gets all knotted and not so fluffy I will replace a portion of it, never all of it.

As for sponges, I have yet to replace any but there is one or two that are starting to really degrade and could be replaced.

For your cartridges, replace them when they start falling apart. It is a good idea to stuff the new media in with the old media for a few weeks so the new one can get a bacteria colony going.

I've never heard of filter floss, I will have to look into it. But that is a good idea to add new media with the old to maintain the bacteria

 

[RayClem]

There are many different types of filter media. Maintenance requirements differ for each type. The filter manufacturers recommend replacing filter media frequently as that is how they make their money. They do not make a lot of money selling filters, but they make a lot of money on the media. especially if you follow their recommendations.

If you use carbon, it needs to be replaced regularly. It removes various things (both wanted and unwanted) from the water indiscriminately. Once the absorbtion capacity of the carbon is reached, some of those substances can start leaching back in to the water. If you have live plants in your tank, activated carbon may do more harm than good by removing some of the nutrients your plants need to thrive. Many fish keepers with planted tanks do not use activated carbon routinely, but do keep some for removing medications, unusual odors, etc.

Filter media used primarily to provide mechanical filtration need to be cleaned regularly. Otherwise, it will get clogged with debris. I use prefilter sponges on all my filter intakes and I have to clean them every week or two when I note the water flow starting to drop. I do not use the expensive replacement cartridges for my HOB filters. I purchase filter pads and cut them to fit my filters. Acurel makes a great filter pad that is stiff enough to work well, yet when it plugs up, you can clean it several times by rinsing in used tank water before it needs replacement. You want to keep mechanical filters fairly clean as the debris will decay and contribute to higher nitrate levels in your tank. The frequency of cleaning will depend upon the stocking of your tank and the types and amount of foods you feed.

Filter sponges, whether used as prefilters, an air driven sponge filter, or a sponge in your HOB or canister filter will provide both mechanical and biological filtration. They will need to be cleaned periodically by rinsing in used tank water. Never expose them to chlorinated water as this will kill some of the beneficial bacteria inhabiting the pores of the sponge.

Biological media such as bioballs, pot scrubbers, ceramic rings, lava rock, pumice or expensive manufactured biomedia will need to be rinsed if they become clogged with debris. This type of media should always be preceded by mechanical filter media to reduce the frequency of cleaning. It is best to clean only a portion of the media at one time so you do not disrupt the biofilter.

Finally, there is chemical media. All chemical media, whether activated carbon, granular ferric oxide, ceramic bead for removal of phosphates, Purigen, ChemiPure or PolyFilter will eventually become exhausted. Some types can be regenerated and other types have to be replaced. Check with specific manufacturer instructions.

 

[Theulli]

The one you want to regularly change is the carbon filter, because they may eventually leach back into the tank when they are spent.

The other ones, I would literally never replace unless you see them degrading (as can happen with some biological media), and then you want a bunch of lead time to seed the replacement. You can even get some bio media that doesn't degrade at all (ex: Seachem Matrix) - then you're basically down to just needing to pull everything out once a month and gently whisk it around in some tank water to remove debris.

Most companies overstate how often you need to replace things because they want that continual source of income.