# Canister filter get really dirty if you don't clean them in a while.



## SpaceLord (Feb 29, 2016)

Ok, I was under the impression that canister filters could go a while without cleaning. 

When If first got my canister filter, I open it a few weeks in and it was relatively clean. I went on a few week vacation came back and it was clean. 

I felt that since those HOB filters take a while to get dirty and a canister filter had like 50 times the filter media, then it would last 50 times as long. 

So I went like 5 months without cleaning my filter on an overstocked tank and today, holly molly, that thing was as black as black could be. I could not even tell what I was looking at it was so dirty!!! It was so black that I think it was sucking in surrounding light like a black hole in outer space. 

I am never going to wait that long again. In fact, I am going to add a second filter to the tank. I just wanted to warn everyone to clean their canister filter often. 

What is the normal amount of time you are suppose to wait until changing a canister filter? 

Thanks.


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## OVT (Nov 29, 2011)

Depends on the filter and the tank.


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## gmh (Jul 16, 2014)

Yeah, there are too many variables to predict when you need to clean the canister. 5 months is a long time however. I clean my rena xpl on my big tank every 10 weeks but my Eheim 2013 on my 20 gallon gets cleaned maybe every 5 months. That tank has low flow and low stocking level.


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## Immortal1 (Feb 18, 2015)

Once a month for me using eheim pro 4 on an overstocked 75g tank.


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## AbbeysDad (Apr 13, 2016)

The really odd thing is that some think the filter is removing detritus so the tank is clean. In fact, all it's doing is sweeping the crud under the rug so to speak...out of sight out of mind. In fact, all that waste continues to break down into nitrogenous compounds that ultimately creates nitrates. Now in a heavily planted tank, this can be a good thing as in theory, the filter creates organic fertilizer for the plants. Still, in a well stocked tank, it needs to be monitored so as not to cause an unwanted imbalance. 
Just my nickel, but I'd say regardless of the filter size, tank size and bio-load, filters should be checked/cleaned at least every month and more often if/when it's found to be very dirty after the month.


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## Rob in (ca) (Aug 24, 2012)

Not cleaning your canister filter for long periods of time, also leads to higher phosphates Levels, because of all the uneaten fish food, Gets trapped in your canister. Last thing you want in a high lighted plant tank is elevated phosphates levels.


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## natemcnutty (May 26, 2016)

Filters get exponentially dirty, and this applies to any kind of filter (car, house, fish tank). They are designed to catch undesirable things, and as more collected, stuff that would normally have gone through will now get caught. 

So really, filters get more effective as they do their job, and actually you don't want to clean too frequently. But you also don't want to wait to long either  

Sent from my Nexus 6 using Tapatalk


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## jrill (Nov 20, 2013)

Rob in (ca) said:


> Not cleaning your canister filter for long periods of time, also leads to higher phosphates Levels, because of all the uneaten fish food, Gets trapped in your canister. Last thing you want in a high lighted plant tank is elevated phosphates levels.


Noooo, you want somewhat elevated phosphate levels in a planted tank.
I clean mine once a month.

Sent from my XT1585 using Tapatalk


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## OVT (Nov 29, 2011)

Maybe a bit off topic, maybe. How do you know when to change oil in your car?

Some years back, US Army tried to outsource R&D to answer that question. If you have the answer, they have some $$$ for you. Just think how much money just-in-time oil change can save, not to mention how green it would be.

I believe the same applies to aquarium filters - a simple question with many faucets and variables.


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## MChambers (May 26, 2009)

*Interesting questino*



SpaceLord said:


> Ok, I was under the impression that canister filters could go a while without cleaning.
> 
> When If first got my canister filter, I open it a few weeks in and it was relatively clean. I went on a few week vacation came back and it was clean.
> 
> ...


You've asked an interesting question and one that provokes very strong views, on both sides of the debate.

Some folks think that the waste accumulating in a canister is bad for water quality; others disagree. Personally, I don't think the waste causes problems, because I think one removes any excess nitrates and phosphates by frequent water changes. After all, the nitrates and phosphates are soluble. But I've never seen any scientific studies that examine this directly. I do think Dr. Tanner's article on filtration, and mattenfilters, suggest that cleaning a filter is not necessary as long as the flow is fine.

Aquarium Biofiltration - SWISSTROPICALS


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## dukydaf (Dec 27, 2004)

Very axiomatic title, just like beer gets warm if you leave it in the sun a while. :tongue:


SpaceLord said:


> What is the normal amount of time you are suppose to wait until *changing* a canister filter?


To answer your question strictly, most people wait until the pump fails or the housing breaks down. Some find out that they need to upgrade and then they* change* their filter. If you have an Eheim this can be several years or decades. However, you should clean it before it stops dead. Just open it and wash the media in a bucket filled with aquarium water. Cleaning canister filters has been found to help with the flow as well as reducing organics in the aquarium.

I see most people here refer to how often one should clean the filter media and have covered the subject pretty well. After you disturbed the substrate , clean your filter. When you see BBA bloom out of nowhere, clean your filter. 




MChambers said:


> Some folks think that the waste accumulating in a canister is bad for water quality; others disagree. Personally, I don't think the waste causes problems, because I think one removes any excess nitrates and phosphates by frequent water changes. After all, the nitrates and phosphates are soluble.


Most of the aquarists, myself included, start with fish and then add plants. Hence the first things we learn about apply to fish aquariums. It can be quite hard to change some of these believes. When you have fish-only tanks you have nightmares about high NO3, high PO4 etc. 

High NO3 and high PO4 alone do not cause algae. In aquariums with high light, good CO2 and fast growing plants you will run out of PO4 and NO3, if you rely only on fish food. Once you run out you will have problems with the plants and algae.

Why did fish keepers associate high NO3 with algae ? Why can we add NO3 to the aquarium and not get algae ? Is there an attempt to fool us ? 

Think about it, they do not add inorganic NO3, so all the NO3 comes from the breaking down of NO2, which comes from NH4 - which comes from many other molecules- which come from the gunk in your filter or substrate. It is these upstream molecules that induce algae germination. NH4 and even before that are the stuff you want to remove/reduce from your aquarium. This issue becomes a little less critical when you have lots of healthy fast growing plants which are able to take up some of the NH4. Another way can reduce this substance by cleaning the filter, cleaning damaged plants, the substrate etc.


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## houseofcards (Mar 21, 2009)

dukydaf said:


> ....
> 
> ..Think about it, they do not add inorganic NO3, so all the NO3 comes from the breaking down of NO2, which comes from NH4 - which comes from many other molecules- which come from the gunk in your filter or substrate. It is these upstream molecules that induce algae germination. NH4 and even before that are the stuff you want to remove/reduce from your aquarium. This issue becomes a little less critical when you have lots of healthy fast growing plants which are able to take up some of the NH4. Another way can reduce this substance by cleaning the filter, cleaning damaged plants, the substrate etc.


Exactly. That's why it's always better to add NO3, then rely on NO3 from organic breakdown in your tank. When you do this with water changes and other organic removal processes your will have far less algae problems regardless of plant mass, fish load.


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## Jaguar (Oct 13, 2011)

I add NO3 and PO4 to my tank. I like to live dangerously 

I've gone as long as 6 months and as short as a week between cleanings. Running at maintenance for the 6 months, substrate change & huge amount of plant melt during the 1 week. I generally leave it alone unless flow starts slowing down.


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## Maryland Guppy (Dec 6, 2014)

When the waving of the plants slows down a bit I'm in the canister.
Sometimes this is 2 weeks if I cleanup and trim.
Sometimes 3 months if I let it go wild.

We all need our own indicator from within our tank IMO.


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## Nordic (Nov 11, 2003)

I see them as crap teabags, no point doing a water change if you are just going to run it through a dirty filter again.
I think most people make the mistake of trying to "clean" a filter. I just run some water from the tank into a bucket, then squeeze out filter material, it should only take some seconds to get most of the visible stuff off. Then do the rest of the water change.

How long your filter can go has lots to do with bioload too. My favourite tank in terms of heavy load, as an Millenium hob on, I added a large sponge to the intake. The filter material inside almost doesn't even change colour anymore. There is just way too much better places to grow. Especially if I take into account it also has a plastic grid through which it blows bubbles.

There is just never a good enough reason not to do a quick cleaning of the filter if you are working on the tank anyway. My fish are a big investment, so I try to stay ahead of their needs rather than waiting on tests and visible cues.


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## Smooch (May 14, 2016)

I completely agree, Nordic.

I don't have canister filters as I can't stand them, so I use HOB's. I used to clean them out monthly while rinsing filter pads with every water change, but since I had that one outbreak with ich a couple of weeks ago, squeezing out sponges along with pads is a weekly thing now. The ich issue has come and gone, but it seems to have deepened my OCD when it comes to tank cleaning along with gear such as siphons, ect...

Yesterday was tank maintenance day. I did my usual thing but found that for the 2 tanks that have 2 filters, only one side really collected any crud while the other side was fairly clean. It was a odd, but everything got rinsed anyway. 

I equate dirty filters to sitting the tub in one's own filth. No offense to those that enjoy a bath.


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## Olskule (Jan 28, 2010)

When the filter material becomes filled and more clogged, the aerobic bacteria have less oxygenated water flow to break down ammonia and nitrite into nitrate, which plants use, but nitrate can build up in the aquarium if water changes are not performed. However, as aerobic bacteria dies off in the absence of oxygen due to the reduced flow, it is replaced by anaerobic bacteria, which further breaks down nitrate and other wastes into free nitrogen (which mostly leaves the aquarium as a gas) and into other nutrients that plants can use, so anaerobic bacteria isn't all bad. But another product of anaerobic bacteria is hydrogen sulfide (you know, that "rotten egg" or sewage smell?) and other toxins, which was the cause of "sudden tank-death syndrome" way back in the early days of aquarium keeping, before UG filters, power filters, and before affordable artificial lighting was sufficient for growing many plants. (Basically what was happening was a substrate--usually fine gravel or sand--was too deep and went undisturbed for a long period, and then something dug a little too deep and hit a pocket of anaerobic bacteria, releasing the hydrogen sulfide and killing everything in the aquarium.) 

That said, in his book, "Encyclopedia of Aquarium Plants", Peter Hiscock recommends allowing part of the filter medium to become partly anaerobic by alternating the rinsing of half the medium and leaving the other half " dirty" and somewhat clogged, and rinsing that half the next time the filter is cleaned, leaving the other half unrinsed. This is said to naturally provide nutrients for the aquarium plants. Whether you prescribe to this train of thought or not probably depends on your personal degree of anal-retentiveness, but I imagine a small degree of anaerobic activity in a filter that is regularly cleaned may be beneficial to plants, but wouldn't do a thing for animals, other than potentially harm them. Besides that, most hobbyists here are artificially providing nutrients by dosing in controlled measure, although if you wanted to achieve a balanced, fully closed "natural" aquarium system without any additions other than light and topping off the water level, it might have merit.

As has been stated above, it all depends upon many variables, including your intentions for the aquarium, the animal stocking load, the plant stocking, how much you feed the animals, what scavengers you have, etc.

I just bought a setup that included two Fluval 305s, which I immediately put on a 55 without cleaning. (The 55 is newly set up, specifically for three plecos that came with the new setup, so I wasn't concerned about introducing anything harmful to an established aquarium, plus I wanted the ready-made nitrogen cycle for the plecos.) When I noticed the flow was practically nil, I broke one down to see what the problem was. The filter pads were so clogged and full of what can only be described as "mud" that a filter basket filled with filter pads in the bottom and ceramic bio-medium on top of that actually floated in the bucket for several minutes, until I got impatient and pushed it under. Now THAT'S a dirty filter!

Olskule


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## smackpixi (Feb 14, 2009)

Unclean filters are nitrate factories. This is a problem in any saltwater setup, that's why they don't use canisters. It's a problem in a fish only freshwater, need to clean the filter, often. Doesn't matter in a heavily planted tank, monitor your NPK levels and dose accordingly with your unclean filter supplementing. Clean canister when flow drops to a level you don't like. I clean mine once a year just for the heck of it....the only thing in my filters is ceramic bio media.


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## dukydaf (Dec 27, 2004)

Olskule said:


> ...I imagine a small degree of anaerobic activity in a filter ... wouldn't do a thing for animals, other than potentially harm them.


:grin2:

Good point @Olskule . The whole NO3 reducing conditions is again aimed for fish-only setups. It will remove bioavailable N from the system thus will not provide nutrients for plants, naturally or otherwise. As you rightly say, bacteria that grows in anaerobic conditions will create all sorts of nasty bi-products, most of them poisonous to higher life forms H2S, CH4...The nice NO3 will be converted back to the very lethal NO2 in the process towards N2 gas, not sure I want that being pushed by the canister in the aquarium. It will also make some metals back into bioavailable/reactive form... such as Fe but also Cu, Pb. I hope you see by now why anaerboic bacteria have no place in the filter ( in addition to what I mentioned in the previous post). 

The only time I have seen anaerobic areas in the filter was when it was powered off for more than 3 days. Unless the canister filter has a very quick bypass or is designed to have no flow areas, it would be very hard to create anaerobic conditions when new oxygenated water flows by.

That being said, I have nothing against anaerobic areas. Their place is in the substrate and in limited amount. 

The more we understand natural ecosystem, the more we realize our aquariums are far from natural. The faster we realize that we cannot create a natural ecosystem in our glass box, the better we become at keeping plants and fish alive and well.


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## Jaye (Mar 11, 2015)

Maryland Guppy said:


> When the waving of the plants slows down a bit I'm in the canister.


This is me. When I first started my 29, I cleaned the filter every other week. Now it's more like every three months. As the tank has matured, it definitely throws off less detritus. OTOH, on the 125, which is about two months old, I change the floss pretty much every night, and the socks the floss sits in at least weekly.


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## AbbeysDad (Apr 13, 2016)

It is nearly impossible to culture anaerobic bacteria in a freshwater aquarium filter with any flow through it. There's just too much O2. You could in a filter that gets turned off and just sits for days. But lets not assume that all anaerobic bacteria is the kind that will convert nitrates into nitrogen gas. Moreover are the decomposition types that make good water putrid.
Also lets be clear - it is aerobic decomposition bacteria (not anaerobic and different than the beneficial bacteria in the N2 cycle) that typically decomposes detritus, food and plant waste in the filter and the substrate into plant usable nutrients. You would typically only find anaerobic bacteria in deep sand or under decor like rocks where oxygenated water does not flow....and then only if there is an ample food source.


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## TwoTurtles (Jul 18, 2016)

In ideal circumstances it's very different to a car oil filter. 
The job of a car oil filter is to trap bits of suspended solid material so that they don't damage the engine, eventually the filter fills up with that solid material so you have to change it. 
The primary job of a canister filter is to convert dissolved ammonia in to dissolved nitrate. The nitrate isn't removed from the system by the filter, that's done either by plants or by water changes. Therefore nothing is building up in the filter, so nothing needs changing ever.

That's the ideal situation and it only accounts for the primary job of the canister filter. A secondary job is removing suspended solids so your mechanical layer will need changing eventually. Also, Nitrosomonas and Nitrobacter aren't the only things living in your filter, there is other stuff growing there which is less desirable so that needs removing eventually.

All that theory doesn't actually tell you when you should clean your filter. But it does give me a chance to check if I understand filters correctly (please tell me if I'm wrong). Personally I'm going to go for every month or when I see less waving of the plants as that seems to be the consensus.


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## Smooch (May 14, 2016)

TwoTurtles said:


> The primary job of a canister filter is to convert dissolved ammonia in to dissolved nitrate. The nitrate isn't removed from the system by the filter, that's done either by plants or by water changes. Therefore nothing is building up in the filter, so nothing needs changing ever.


I challenge anybody with a canister filter to test the disgusting water that they accumulate to see of this is true or not. The answer is not, but since you feel as though there is no way filters can hold on to said gunk, test it for yourself. All the fish food, fish poop, dead leaves and whatever else that goes into the filter that sits around brewing like a foul-smelling stew does not simply go away because a person has a planted tank. Filter pads and sponges need to be rinsed, bio media can become overloaded with crap so it no longer functions properly, ect...


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