# Flooding canister filters?



## Ankhari (Apr 30, 2018)

I'm considering a canister filter and have heard the scary stories about flooding.

Can a canister siphon the entire tank onto the floor or cause major flooding? How likely is that? 

Is this internet exaggeration or is it likely? Anyone had it happen? 

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## aquaoz (Jul 17, 2019)

Ankhari said:


> Can a canister siphon the entire tank onto the floor or cause major flooding? How likely is that?
> 
> Is this internet exaggeration or is it likely? Anyone had it happen?


Possible, not likley....been keeping fish for close to 20 years. Never had a Canister fail in that way before. I'm sure others here will testify similar.


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## AcidGambit (Aug 30, 2018)

A canister filter cannot siphon the entire tank onto the floor unless either your intake or outflow goes all the way to the bottom of your tank. Essentially, the lowest air-break will stop the siphon and stop the canister from pulling more water out of the tank in a catastrophic event. There are a few things you can do to prevent it. For example, you can put your canister filter in a container to contain minor floods. I did this and I have a leak sensor in the container that will shut off my filter if it senses water in the container. Similarly, I have a flood sensor on the floor under my stand that does the same thing.

This topic seems to come up more with saltwater tanks, maybe due to the prevalence of sumps. Look up "siphon break" for more ideas.


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## talontsiawd (Oct 19, 2008)

Like the above poster said, it won't drain the entire tank, how much is possible depends on where your inflow or outflow is placed, whatever is lower. None of us would use canisters if this was common. Canisters can leak, either from a bad seal on the actual canister, a hose on the canister, and more so when you start adding inline components, especially if they are not of the highest quality. For a canister to flood at any real magnitude, a hose would actually have to pop off, something I have never seen, but I could see it happen if the user hooked something up that was the wrong size and just didn't even think about how it is supposed to work. I am sure many of us have had leaks but nothing that would ever exit the stand. Many put the canister in small tub, which would typically make this no problem at all, as even if something leaks above the canister, the water often just follows the tubing back down, depending on how it is setup. 

Truth be told, I have probably drained more than a few gallons out by accident, over many years, opening a valve thinking my canister is hooked up, or some mistake, but I mostly just have had minor leaks that were easy to find. I think the biggest PITA about them is when you find a leak, on say a Monday night, and it's an inline component you can't get ASAP. I keep barbed connectors so I don't have to wait for that component on hand for that reason. Contrarily, I have probably split more water servicing HOB filters, or knocking over a cup even more so to me, it's not a concern. My aquarium is on carpet and most of mine have been. 

I don't want to say you couldn't drain 80-90% of your tank if your outflow ways really low and something really bad happened, it can, but it's just so unlikely. I leaky faucet or pipe could literally flood your home but most of us are still content using indoor plumbing.


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## Ankhari (Apr 30, 2018)

AcidGambit said:


> For example, you can put your canister filter in a container to contain minor floods. I did this and I have a leak sensor in the container that will shut off my filter if it senses water in the container.


Thanks for the info. I hadn't worked through the logistics of air interrupting the siphon. 

What kind of sensor is it? The leak sensors I briefly looked into were more of an alarm.

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## Ankhari (Apr 30, 2018)

talontsiawd said:


> My aquarium is on carpet and most of mine have been.
> 
> but most of us are still content using indoor plumbing.


The hesitation was that plumbing leaks from a faucet fall into the landlord's problem, but an aquarium leak is very much my problem. 

Thanks for the reassurance!

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## AcidGambit (Aug 30, 2018)

Ankhari said:


> Thanks for the info. I hadn't worked through the logistics of air interrupting the siphon.
> 
> What kind of sensor is it? The leak sensors I briefly looked into were more of an alarm.
> 
> Sent from my Pixel using Tapatalk


It is a z-wave flood sensor that reports to my home automation system. My aquarium components are on a z-wave power strip so I can use code to turn them on and off. I wrote code that shuts off the filter if either z-wave flood sensor reports water and then I also get a notification on my phone.

I didn't start using home automation for this purpose, so it would probably be overkill to do for just this purpose. But there may be flood sensors that allow you to kill power when they sense water, I just haven't looked for them.


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## Frank158 (Oct 1, 2013)

Ankhari said:


> I'm considering a canister filter and have heard the scary stories about flooding.
> 
> Can a canister siphon the entire tank onto the floor or cause major flooding? How likely is that?
> 
> ...



Yup if any kind of leak happens to the outflow the canister will shoot water all over the place. Happened to me once where my spray bar got loose (old suction cups no longer suctioning) so the spray was shooting out of the tank. I cam home to half a tank and a wet carpet. 

So yes it can happen (unlikely) but it can. That said I still use canister filters and sleep well at night.


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## KayakJimW (Aug 12, 2016)

I've heard of folks drilling a tiny hole in the back of their intake tube below the water line. That should break the siphon once the water falls below it


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## united natures (May 15, 2019)

If you setup the filter properly and secure the hoses and attach them securely to your tank then leaks shouldnt happen


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## talontsiawd (Oct 19, 2008)

Ankhari said:


> The hesitation was that plumbing leaks from a faucet fall into the landlord's problem, but an aquarium leak is very much my problem.
> 
> Thanks for the reassurance!
> 
> Sent from my Pixel using Tapatalk


I can understand that, again, it's not without risk but if you set everything up right and buy quality inline products if you choose to add them, you shouldn't have much problems, maybe a small leak (you should definitely look for them any time you change anything with the plumbing for a few days when doing other things on the tank). 

Truth be told, I personally don't see a huge disadvantage of staying with a HOB. I have never used an internal filter but they seem both inefficient and take up a lot of space (and are not attractive). For me, the main benefit of a canister filter is noise, second is appearance. Canister filters require maintenance less often but it's more involved. I think HOB filters are underrated on this board.


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## aquanerd13 (Jun 22, 2019)

Put you canister in a plastic container and put water alarms everywhere.


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## Amp2020 (Mar 8, 2013)

Most of my canister filters are second hand. Either bought them dirt cheap or were free because they leak or had broken parts. The o-rings are easy to replace if they leaked. I still keep them in an empty cat litter bucket with a Watchdog water alarm inside. Never had a tank drain but had several times were a canister leaked slowly. If I didn't catch the leak in time, it could have ruined my hardwood floors. The bucket is free after using up the cat litter and the water alarm was under $20 at home depot several years ago.

Worst story I've ever heard was when a client of mine called me for help after his vacation trip. The hose popped off the canister filter and all but 2" of water were drained from his 55 gallon tank. Fish were still alive but it cost him over $10k in damages to the carpets, subflooring, dry wall in that room and room below, ceiling below, and downstairs hardwood floor. So use hose clamps on all barbed fittings.


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## Frank158 (Oct 1, 2013)

Amp2020 said:


> Worst story I've ever heard was when a client of mine called me for help after his vacation trip. The hose popped off the canister filter and all but 2" of water were drained from his 55 gallon tank. Fish were still alive but it cost him over $10k in damages to the carpets, subflooring, dry wall in that room and room below, ceiling below, and downstairs hardwood floor. So use hose clamps on all barbed fittings.


Yes that is why one should always have some kind of home owner's insurance. I have a 40+ gallon set up upstairs and right underneath it is a finished basement and the home stereo system. If that tank goes for any reason I am covered. At least financially. 

To the original poster, set it up right. Make sure of your connections and have insurance just in case an accident happens. Sleep well and don't worry. >


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## somewhatshocked (Aug 8, 2011)

Like @talontsiawd and others have suggested, it's pretty easy to be prepared. Once you get things running, you'll feel more confident. Also handy to have spare parts on-hand like o rings and connectors. I've broken two Eheim connectors in 20+ years and I've been glad to have had spares at those times. 

I've never had an o ring/gasket fail on a filter but I have replaced a few through the years due to wear and tear.

You're likely to find that the only issues you'll have are attributable to user error. I changed about 100 gallons of water this morning across a dozen tanks and didn't get a drop of water anywhere. Not even on the towel I put down in front of each tank. But I got soaked - twice - trying to pour water down the drain into my gray water system because I didn't check to see if there was anything in the sink. Twice! In a 20 minute timespan.


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## PlantedRich (Jul 21, 2010)

I use lots of canisters an d try to avoid all the others but have never had a major leak from the filters. Slow oozes or not checking that I've put the lid back on correctly are far more common, and for those. I have all cans setting in plastic dishpans with the cheap alarms alongside to alert me when the dishpan gets wet. I call it $7 worth of insurance and get them off E-bay. 
It still doesn't stop the flood when I leave a hose running! 
:icon_roll


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## JJ09 (Sep 11, 2014)

User error, here. I had a canister on my 38gal (no longer have the tank). When I first set up the canister I screwed one of the fittings too tight in my eagerness to have it really snug, and cracked the housing. It had a very slow leak, glad I had set it in a large tupperware container and found the problem when there was an inch of water in the tupperware. Did a temporary patch and bought replacement housing; I was a lot more careful the second time around.


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## Cyano (Jul 8, 2018)

I'm with everyone else... been using canisters for a long, long time. Never had a disaster. Had a slow drip once from a Marineland-brand canister. Never lost a drop with a Fluval or API Filstar. 

Use hose clamps, put the filter into a bucket of some kind, and use water alarms. The odds are in your favor.


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## Triport (Sep 3, 2017)

My canister filter failures have always been at the time of cleaning (or in one case when new and priming) and either stem from me being dumb and forgetting to turn the release valves or from a piece of plastic breaking when priming. So yes I have spilled water on the floor but only when I was there to address the situation. Now I just always have towels on hand when working with filters. I've never had one break and empty the tank onto the floor when I wasn't there.


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## toriless (Jun 4, 2014)

Ankhari said:


> I'm considering a canister filter and have heard the scary stories about flooding.
> 
> Can a canister siphon the entire tank onto the floor or cause major flooding? How likely is that?
> 
> Is this internet exaggeration or is it likely? Anyone had it happen?


Not if you set it up right, you just need to set the intake near the top of the tank and turn it off during water changes. Once the water get below that level suction will be broken. You are more likely to have issues from leaks unless you use hose clamps but not drain the tank, just a hose, it happened to to me once before I put hose clamps on. As usual, there are moron all across the internet who do not know how to proper set up your tank to avoid such disasters. Same for the return.

Bump: I had a hose leak and I put a hose clamp on it but not a leaking canister.


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