# siphon break hole in canister intake?



## milesm (Apr 4, 2006)

i've never used a canister filter before. im paranoid about my tank draining if problems with my new eheim 2213 were to arise. the intake tube seems to take water from the bottom of the tank, so if there is a leak in the canister, it would drain the entire tank.

drilling a small hole nearer to the surface would limit water loss to that point. is this practical with a canister? does it affect the priming? i realize the canister would be running dry and that could cause motor problems, but that would be a small pittance compared to soaked flooring, a completely drained tank, and a dry running motor. thanks.


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## BiscuitSlayer (Apr 1, 2005)

milesm -

Thats a good question. I know what you are talking about because that is exactly what I did with the water return from a sump at one point. I drilled a hole in the return so that if the water fell below the drill hole it would break the syphon.

I am interested to see what people reply with.


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## Complexity (Jan 30, 2008)

milesm said:


> the intake tube seems to take water from the bottom of the tank...


I'm confused. The intake tube normally doesn't require any holes to be drilled at all. The tubing goes over the top rim of the tank.

Look at the pictures of how the tubing goes over the top of the tank. No holes drilled whatsoever.

http://eheim.com/base/eheim/inhalte/indexf458.html?key=liniendetail_27510_ehen


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## BiscuitSlayer (Apr 1, 2005)

Complexity said:


> I'm confused. The intake tube normally doesn't require any holes to be drilled at all. The tubing goes over the top rim of the tank.


Complexity -

The question isn't wether the holes should be there or not, the question is "Can he drill hole(s)?"

The point is so that if the canister was to develop a leak such as a bad seal, then it would only leak down to the hole he drilled and then the syphon would be broken.

I am not advocating drilling holes in anything, but I do understand the reasoning.


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## Complexity (Jan 30, 2008)

BiscuitSlayer, I understand what you're saying. But I don't think that's what the OP is asking.

Please look at the parts I'm have emphasized from his original post.



milesm said:


> *i've never used a canister filter before*. im paranoid about my tank draining if problems with my *new eheim 2213* were to arise. *the intake tube seems to take water from the bottom of the tank*, so if there is a leak in the canister, it would drain the entire tank.


What I understand is that he's trying to install his very first canister and is confused as to where the intake tube goes. It's not that he _wants_ to drill a hole, but he thinks he's _supposed_ to.


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## lescarpentier (Feb 2, 2008)

BiscuitSlayer said:


> I am not advocating drilling holes in anything, but I do understand the reasoning.


My thoughts exactly.I trust my connections and my filters,however,for the more paranoid of mind maybe a safeguard is really not that bad of an idea.If you are going to be stressed about it,drill the hole.I would drill the hole far enough below the surface so that you don't lose your siphon when you do large water changes.


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## Complexity (Jan 30, 2008)

I guess I'm just not getting it.

How could drilling a hole below the water line be better than having the tube going over the top of the tank?

Either way, it's where the actual intake screen is placed that matters. You can drill a hole and put the hose through it at 12" from the bottom of the tank, but the syphon won't break until the actual intake screen starts sucking air. So if that intake screen is only 3" from the bottom, then the hole at 12" is pointless.

If there is a fear of syphoning the entire tank, the solution is to put the intake screen close to the top of the tank. Not very efficient, but it will break the syphon with less water drained. This is true regardless of where the hose goes from the outside of the tank to the inside.


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## BiscuitSlayer (Apr 1, 2005)

Complexity said:


> I guess I'm just not getting it.
> 
> How could drilling a hole below the water line be better than having the tube going over the top of the tank?
> 
> ...



Lets say that you drill a hole in the canister intake tube 1" below the waterline for the tank. If something was to happen to the canister filter in regards to a leak, it would only syphon out 1" of water from your tank. 

Without the hole, it would syphon out pretty much everything until it got to the bottom of the intake tube and the syphon was then broken.

Make sense?


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## Complexity (Jan 30, 2008)

Wait a minute.

I'm thinking you're all talking about drilling a hole in the glass tank! It just hit me. He's talking about putting a small hole in the actual intake tubing, not the glass.

When I read the part "seems to take water from the bottom of the tank", my mind thought of the tank itself. The glass.

Okay, now I get it. And, yes, drilling a hole would be an interesting solution. Not a bad idea at all.


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## lescarpentier (Feb 2, 2008)

Complexity said:


> I guess I'm just not getting it.
> How could drilling a hole below the water line be better than having the tube going over the top of the tank?


Complexity,
With the way we are explaining it,everything is hooked up like normal,lift tube over the top,&c.,except a hole is drilled in the lift tube below the surface of the water so that the siphon would be broken in the event of a leak.


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## Complexity (Jan 30, 2008)

BiscuitSlayer said:


> Lets say that you drill a hole in the canister intake tube 1" below the waterline for the tank. If something was to happen to the canister filter in regards to a leak, it would only syphon out 1" of water from your tank.
> 
> Without the hole, it would syphon out pretty much everything until it got to the bottom of the intake tube and the syphon was then broken.
> 
> Make sense?


Makes perfect sense now that I understand where the hole is being drilled. I was typing while you were posting. I get it now.

Where's the "hit your head with your hand" icon when you need one?


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## BiscuitSlayer (Apr 1, 2005)

Complexity said:


> Wait a minute.
> 
> I'm thinking you're all talking about drilling a hole in the glass tank! It just hit me. He's talking about putting a small hole in the actual intake tubing, not the glass.
> 
> ...



It is a common practice with people that have sump driven systems. Ideally, you want your sump return to have a hole slightly below your "running" waterline in the main tank. That way, you don't have to worry about too much water being syphoned back into the sump if your sump pump stops working due to a power failure or some other type of failure.


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## Complexity (Jan 30, 2008)

BiscuitSlayer said:


> It is a common practice with people that have sump driven systems. Ideally, you want your sump return to have a hole slightly below your "running" waterline in the main tank. That way, you don't have to worry about too much water being syphoned back into the sump if your sump pump stops working due to a power failure or some other type of failure.


I never knew that since I've never had a sump.

Looks like I've learned something new tonight, even if it was a bit hard to get it into my head. :icon_lol:


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## Complexity (Jan 30, 2008)

lescarpentier said:


> I would drill the hole far enough below the surface so that you don't lose your siphon when you do large water changes.


Okay, now that I'm on board with the right understanding of the idea, I wonder if this can be avoided. If he's doing 50% water changes, then he'd still be risking half of his tank draining.

What about an on/off valve placed just above the hole? It's normally on which allows water to flow as normal. If his canister leaks, the hole will break the syphon.

However, when he does a water change, he turns the valve off which locks the water inside the tubing. The hole is below the valve so even though it will suck in air, it won't matter because the water is being held in by the valve.

He fills his tank up, now water comes in through the bottom screen which fills the intake hose from the below the valve. It's now safe to turn the valve back on, allowing the water to flow freely again.

So he gets his hole to break the syphon and he has a valve to do water changes without breaking his syphon. He gets both!

Could that work?

I must add... he would have to turn his canister off when he flipped the valve closed to stop the water flow, and then back on when he finishes filling the tank and flips the valve back open. But that shouldn't cause any problems.


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## lescarpentier (Feb 2, 2008)

Complexity said:


> Could that work?
> I must add... he would have to turn his canister off when he flipped the valve closed to stop the water flow, and then back on when he finishes filling the tank and flips the valve back open.


Yes that would work great,but the question is,"is it worth the trouble"?
My recommendation would be to drill a hole the size that you can get a small rubber plug for.
Before you start your water change you can insert the rubber plug,and remove it when you are finished.This would be a very small inconvenience compared to installing a valve,and having to shut your filter down with every water change.


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## Complexity (Jan 30, 2008)

Whether it's worth the trouble is up to each individual. One man's trash is another man's treasure. Or something like that.

I thought of using a plug, but for me, I would find it a pain in the backside to not lose the plug and to try to get the thing out of the hole each time. I'm assuming it would be a pretty small plug that has to fit in tightly enough to be air (well, water) tight. Not to mention the plug will be wet which makes it slippery. Or I'd have to dry it each time to get a grip on it. Or I'd have to go hunting for some clean needle nose pliers.

For me, it would be worth the trouble. It might be more work to make, but it would be a breeze from that point on. Just turn a knob.

But that's where it becomes fun in which each person gets to decide what works best for them.


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## lescarpentier (Feb 2, 2008)

Complexity said:


> For me, it would be worth the trouble. It might be more work to make, but it would be a breeze from that point on. Just turn a knob.
> But that's where it becomes fun in which each person gets to decide what works best for them.


Without a doubt your idea is the superior one,and is a much more professional choice.I was just thinking about an easy,and inexpensive way to do the same thing.


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## DaveS (Mar 2, 2008)

Eheim was kind enough to send me a cracked intake tube with my filter, so I basically have an emergency siphon break built in to my filter. With my Fluval 404, I ended up drilling a hole in the intake tube just as described in this thread. With the Fluval, getting the filter reprimed was such a simple matter that I just didn't worry about breaking the siphon on waterchanges. The same goes for my Pro II series Eheim, so I guess it just depends how difficult it is to get your filter reprimed. Regardless, you only need to come home from vacation to a drained tank once to see the wisdom of having the siphon break in place.

Dave


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## Complexity (Jan 30, 2008)

lescarpentier said:


> Without a doubt your idea is the superior one,and is a much more professional choice.I was just thinking about an easy,and inexpensive way to do the same thing.


Well, I don't know about superiority or professionalism of any idea. It is just another option to toss into the mixing pot of suggestions.


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## mooner (Dec 2, 2007)

I use both sumps and canisters. IMO, I wouldn't bother drilling a hole anywhere on a canister. I'm not saying that you will never have a leak. Most of us check our tanks several time a day and a leak in a canister would be found long before the tank drains. Now on sumps(with overflows), this is a different story, during a pump failure or a power outage, water will flow in reverse due to the sump isn't a sealed unit as is the canister. Thus, one must drill a hole in the output just below the maintained water level to break such a siphon. Canisters are very reliable and the only trouble had have been from operator errors.


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## milesm (Apr 4, 2006)

well, i guess no one's done it. like biscuit and mooner, i also used one on my sump return on my reef years ago. as to the intake of sump systems, overflow boxes serve the same purpose.

thanks for your input.


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## DaveS (Mar 2, 2008)

Huh? I mentioned that I do it about two posts up. It doesn't cause any major issues and if it gives you peace of mind, then by all means go ahead and do it. I have seen filters leak due to operator error, and I have seen them leak due to poor design. You can assume that neither will affect you, or you can drill the intake. I wish I had drilled the intake tube of my Fluval before it drained my tank, but after that it was lesson learned for me.

Dave


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## milesm (Apr 4, 2006)

DaveS said:


> Huh? I mentioned that I do it about two posts up. It doesn't cause any major issues and if it gives you peace of mind, then by all means go ahead and do it. I have seen filters leak due to operator error, and I have seen them leak due to poor design. You can assume that neither will affect you, or you can drill the intake. I wish I had drilled the intake tube of my Fluval before it drained my tank, but after that it was lesson learned for me.
> 
> Dave


sorry Dave. i did read your post earlier but forgot that you used one on your fluval (and given to you by eheim). i am going to drill a hole about 2" below my nominal water level. i don't mind restarting the intake after water changes.


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