# Are canister Pre-filters recommended?



## Cheetah2 (Nov 24, 2015)

I'm trying to determine whether a pre-filter is necessary for a canister filter. I visualize a sponge covering the intake, but I've also seen one that is added to the tube before the filter (made by Eheim).
Is a pre-filter necessary for anything other than catching larger debris or protecting fish fins? Does it help extend the life of the canister? Are there any cons to adding one?


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## thedood (May 30, 2015)

From my experience a prefilter will greatly reduce the frequency of canister maintenance. You will also find a lot less debris in the canister. I clean my prefilters every other time I do a water change, about twice monthly as I do water changes weekly, but I only clean my canisters every two or three months and then a lot of times it was unnecessary. The only con I can think of is they are somewhat bulky looking. I surround mine with plants and let the plants fill in around the sponge hiding it.


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## Nexgen (Jul 1, 2015)

I don't have any experience with canister filters but I use prefilters on my HOB filters and they keep the contents of the filter cleaner. I don't use the prefilters that you can buy though, I use filter floss that I stitch to fit over the intake.


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## MChambers (May 26, 2009)

I like prefilters on canisters. I think they extend the time between cleanings of the canisters and add another site for the beneficial microorganisms to break down waste.

The principal downside is that you need to keep an eye on your prefilters and clean them at least weekly, in my experience. Depends a lot on the particulars of your tank and filter, of course.


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## thedood (May 30, 2015)

Nexgen said:


> I don't have any experience with canister filters but I use prefilters on my HOB filters and they keep the contents of the filter cleaner. I don't use the prefilters that you can buy though, I use filter floss that I stitch to fit over the intake.


I use quilt batting on my Emperor 400. I actually use zip ties to hold it around the filter. Not real pretty but it works until I do something different.


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## Cheetah2 (Nov 24, 2015)

Thank you for the helpful comments. Filter floss is easier to find than an exact fitting cylindrical sponge.


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## thedood (May 30, 2015)

@Cheetah2 Depends on the filter. For example the ATI Max that I use on two of my canisters fits most round inflows and comes with several adapters to fit different sizes. I did have to use a short piece of 5/8 vinyl tubing to connect it to the inflow on my cascade but one connected right to my magnum. My emperor hob has a rectangular inflow and the only way I know to prefilter it is to make your own. If anyone knows of a prefilter that just works with the emperor let me know as I would by two or three right now.


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## discuspaul (Jul 27, 2010)

In addition to the above, PetSmart stores generally sell the round-shaped Fluval Edge fine mesh pre-filters for about $2.
Fits on most HOB filter intake tubes, particularly well-fitting with AquaClears 30 and above, and should fit on many canister filter intakes as well.
They work like a charm and are quite attractive. Been using them for years - they're very effective if rinsed regularly.


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## PlantedRich (Jul 21, 2010)

I normally don't use pre-filters as they tend to stop up too fast in most of my tanks. Some cases like fry tanks are fine with them to keep fry out of the filter. 
But then I never shop for the exact brand match or such. The filter doesn't have to be round but just run a knife or scissors down into a block of foam. In most cases the sponge will open enough and then close back tight around the intake. On Emperor intakes, I found I needed to cut a semi-rectangle opening for the wide intakes. Since leaking is not really a big thing to worry on sponges, flow is what I want and I find the pore size of Aquaclear sponges is better for my use. Small enough to keep even tiny fry out but not so small that they block flow too much or too quick. I like that I can get one at most shops as they do last a long time in my use.


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## talontsiawd (Oct 19, 2008)

I forget what they are called so I can't find them online but I believe Eheim makes or made a prefilter that was essentially a canister without a motor. I imagine the flow loss would be great. Still some people use those for double the filtration, more or less. Others pay a bit more and just buy another canister, then remove the impeller. This kind of prefilter, never used, but it's very expensive and most of us would rather buy a much bigger filter than needed, for the sole purpose of flow some most of us are arguable over filtered. I have a Eheim 2215 w/ 2217 impeller, and a Ecco 2234 on a 17 gallon, for example, and it's working great for me. It really was an experiment because I had a 2215 laying around, and they do use the same outflow, intake, in parallel, split to each filter (not one feeding the other) so I likely loose some flow but have crazy filtration. No fine pads, less sponges than most would use, a ton of bio and my water is super clear, flow is great, and fish seem healthy.

I sponge on the intake is a much simpler solution. I found when I ran one on my tank, I would clean filter every 6 months and it was in absolutely no need of cleaning. It was almost spotless. However, I found the filter clogged pretty significantly within a week. I was using Fluval ones which are pretty fine. Though I pretty much stopped cleaning my canister, which is harder than cleaning a sponge, I was cleaning sponges so often that it actually was more work overall. Part of what I enjoy about canisters is the longer maintenance intervals so it reminded me of my early days when I was using HOB's and cleaning all the time, well, I cleaned the sponges much more often. A coarser filter would allow for cleaning less often but I couldn't find an attractive option.

Simply put, they have pros and cons. I found with the right filter, it's not bad to clean all the time. I really like my Ecco 2234, for example, because I can easily clean it in the bathroom where my 2215 Classic, I feel it is much harder to clean and is an outside job (though I don't have a back yard anymore, I will see if it stays after I clean it for the first time). Also, once you start adding things like glassware and clear tubing, filter maintenance doesn't seem so bad. It's all relative, I found cleaning the filter helped me wait when bleaching glassware. I now use an ADA spring brush which works just as well or better, but it's more work, and doesn't matter if I am cleaning the filter or not, I can't do both at the same time, but I clean my pipes enough that the filter is no biggie now.

I know that is a really long post for what I am really saying. For a sponge prefilter, it's cheap enough to just try out and see how often you have to clean and if it is too often for your taste, just remove them. Make sure you get two if you decide you like it.


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## Fishbarrie (Feb 13, 2015)

Embarrassed to say I never thought of doing this! I think I will give it a try with my Eheim. Thanks for the tips!!


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## roostertech (Oct 27, 2015)

I cut some bonded pad, wrap it around the intake and zip tie it in place. My shrimps and otos love to eat the craps collected on it. I clean it out on each water change.


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## Leeatl (Aug 8, 2015)

To thedood...I have Emperors and I use the large sponges made for pond pumps.You can get them at Home Depot in the pond dept.They are a tight fit when new.You have to pull each corner up until it covers all the slots.After a while it gets easier to put on.You also have to cut a small piece to put in the end to cover the bottom slots.Hope this helps.


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## thedood (May 30, 2015)

@Leeatl Thanks for the tip. I'm going to look into those.


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## Leeatl (Aug 8, 2015)

Ur welcome!


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## WaterLife (Jul 1, 2015)

talontsiawd said:


> I forget what they are called so I can't find them online but I believe Eheim makes or made a prefilter that was essentially a canister without a motor.


You mean this?
: Amazon.com: Eheim Vorfilter Prefilter 4004320 Part for Aquarium filters NEW
Yeah, to pricey for a prefilter.



Prefilters are great are prolonging the time between performing maintenance on the main canister filter (you clean the easier to access, prefilter instead).

I used to use polyfil (polyester batting) as prefilters on my AquaClear HOB's, but they clog so quickly since they are so fine. Great for mechanically filtering out small particles though. Just are "too good" at trapping particles with their tight weaving so they clog fast. Okay to use temporarily if needed, but too "unsafe" for me to recommend using. Just monitor outflow daily.

The fast clogging reduces filter flow greatly which can be problematic if not corrected soon enough (clogged, slow filter flow = greatly reduced filtration performance, less-no surface agitation/oxygen/aeration, and low-no flow through biomedia keeping beneficial bacteria alive).

I still recommend prefilters, but only prefilters with coarse pores, so they don't clog nearly as fast. Still got to maintain them (same as your main filter media, just this requires more often, given the size and it being the first layer of filtration), but they last a whole lot longer than fine pore prefilters before needing to be cleaned (depends on tank cleanliness).

I use ATI FilterMax (#3 size for my filters - they do come with 3 size adapters though for different sized intake tubing). It uses reticulated sponges. I am sure eBay or the like has cheaper reticulated sponges. The key is coarse pores. So the fine pore sponges still clog pretty fast as well. Of course the thickness of the sponge material makes a difference as well.

There are those Stainless Steel prefilters as well. Come in fine or coarse mesh grating. Haven't used them myself, so I can't comment.


Not really necessary, but worth it to me (much easier to maintain prefilter more often rather than clean the whole canister).


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## discuspaul (Jul 27, 2010)

If one wants to get the most benefit - (translation: effectiveness) - from a pre-filter in terms of keeping as much unwanted matter out of the main filter unit media as possible, to reduce the level & frequency of maintenance & cleansing of the filter unit itself, then a fine mesh pre-filter is the answer.
But fine mesh of course tends to pick up more matter, faster, thereby readily reducing the water flow into & through the filter.
This necessitates frequent rinsing of the pre-filter to allow it to do it's job properly.
Comes with the territory - can't have one without the other. Worth the effort of more frequent rinsing than with coarse mesh pre-filters.


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## Beefyfish (Mar 5, 2015)

I use one side of a shrimp filter like this. It pulls apart and i mod it to fit on intake. 

I clean it evey three weeks when doing a water change. Been using same foam for a year just clean in old tank water. 

This isnt a picture of mine but i can take one when i get home.


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