# New Idea... Canister Filter to Sump?



## [email protected] (Aug 19, 2016)

Greetings all,

I am currently working on an idea to direct my canister outflow into a sump, and have the sump return water to the aquarium with a centrifugal pump. Since my tank isn't drilled and I don't want to worry about losing suction with a pvc or hang on overflow, I came up with this idea. I searched online and while people have used a canister to pull water from a sump and return it to the aquarium, no one has seemed to do it the other way around...

Does anybody have any experience or heard of this? I understand that the return from the sump to the tank would have to be slightly higher in flow rate since the canister is no longer pushing the length upward.

Thoughts?


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## akd200 (Sep 22, 2014)

What kind of a sump are you thinking of?


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## [email protected] (Aug 19, 2016)

akd200 said:


> What kind of a sump are you thinking of?


10 gallon aquarium with an area for a fast growing plant to act as a nutrient sink. Maybe a filter pad and an area for bio media.


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## theDCpump (Jul 22, 2016)

I don't know much about models of canisters or the priming issues involved, but yes and strong canister's pump will raise the water from the sump to the tank.

I'm not sure if the water coming down the canister's intake is helping the pump in a normal canister operation.
It is going to be slurping from the floor and pushing up, so this is a curiously different option.

Try to use buckets, small tanks, and wash tubs etc. for an experiment.

In the end, I would avoid the Murphy's Law on any extra issue to make a sump fail.
You will learn over time if there is an error in this plan.

A pump is unrestricted other than water pushing up.
The canister may block up slowly, change flow ratios and get the sump dialed out-of-wack though.


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## DaveK (Jul 10, 2010)

It would be almost impossible to balance the water flow through the canister with the water flow through the return pump of the sump. Over time, you'll either run the sump dry causing a flood from the display tank, or you'll remove too much water from the display tank overflowing the sump and causing a flood from the sump.

Yes, you can use a canister filter as a return pump, but even there you do need to be careful. If you have a power failure the canister can back siphon. This can also cause a flood. To prevent this you need to take some sction such as using a check valve or drilling the output pipe so that the siphon will break if the water flow stops.

You have a couple of ways you can go that will work.

Keep the canister and sump operation completely separate. This way one can't easily mess up the other. 

Just don't use the canister. Once you have the sump going, you really don't need it.

Either way you will need some form of overflow. This can be done either by drilling the tank or by getting a siphon based overflow such as Lifereef or Eshopps. Be careful with your overflow selection. Some of the other manufacturers offer siphon overflows that have inherent design defects that will cause floods.


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## jrill (Nov 20, 2013)

Like Dave said, bad idea.

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## Bunsen Honeydew (Feb 21, 2017)

If you don't want to worry about a HOB overflow failing, get an aqualifter pump that can be plumbed into the top of a U siphon to reprime it if needed. If a HOB overflow is set up correctly, it is difficult to lose prime.


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## KayakJimW (Aug 12, 2016)

Sorry to burst bubbles, but if there's even a 1 gph difference between canister and return pump, you'd have 24 gallons of water in the wrong place after 1 day. Even if you set it up perfectly at first, the canister flow will reduce once it starts collecting debris and fall behind

With a canister by itself, the closed loop makes outflow and inflow equal. With a sump, your return pump will determine how much water falls into the sump. Having two separate motors independently pushing and pulling water at the same time would not equal out. One will outdo the other.


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## [email protected] (Aug 19, 2016)

Thank you for all that chimed in, but it still leaves me with questions... 

On the subject of the two pumps competing or eventual different displacement... how is this different than an overflow change. I know that sometimes overflows will change displacement for any number of reasons, and from what I understood the difference would just be compensated by the pump in the sump. Not sure the voodoo behind it, but if I have the canister pumping water into the sump, and have as close to the same rated gph pump returning it, shouldn't it take a very long time, longer than a week of topping evap off in the sump for the difference to be drastic?


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## Speaker73 (May 1, 2010)

[email protected] said:


> Thank you for all that chimed in, but it still leaves me with questions...
> 
> On the subject of the two pumps competing or eventual different displacement... how is this different than an overflow change. I know that sometimes overflows will change displacement for any number of reasons, and from what I understood the difference would just be compensated by the pump in the sump. Not sure the voodoo behind it, but if I have the canister pumping water into the sump, and have as close to the same rated gph pump returning it, shouldn't it take a very long time, longer than a week of topping evap off in the sump for the difference to be drastic?


With an overflow, sump and return pump the pump returns water to the tank that fills up and once the level is high enough the water goes to the sump via the overflow due to gravity. Thus the overflow is equal to the return flow. It's a sort of modified closed loop system. 

With two different pumps the flow rates will be different so you'll either overflow the tank or the sump eventually. I HIGHLY recommend that you take the advice of people here to avoid unnecessary incidents. 

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## DaveK (Jul 10, 2010)

Bunsen Honeydew said:


> If you don't want to worry about a HOB overflow failing, get an aqualifter pump that can be plumbed into the top of a U siphon to reprime it if needed. If a HOB overflow is set up correctly, it is difficult to lose prime.


In my opinion, trying to use an Aqualifter pump, especially with a CPR overflow as in your picture is a recipe for disaster. You have several problems here.

The Aqualifter pump is not that reliable. It often just quits working. This is because it uses a very simple check valve system that is just a couple flaps of rubber. These can fail easily because they can get clogged or they fail to seal. Also due to the small diameter of everything, the pump or tubing easily gets clogged.

The connection on the overflow siphon is easily broken off. While it can be repaired, if you don't see it, the siphon fails.

You also have some problems with the CPR overflow itself, unrelated to the Aqualifter pump. 

The U tube is almost impossible to clean. It's molded into the overflow. Because of this, it will collect bacteria, algae and other dirt. When this comes off, it can easily clog the connection that you connect the Aqualifter pump to. 

Because of the tight angles of the siphon, it's possible for snails and similar stuff to go up the siphon and get stuck inside it. This leads to clogging problems, because of the difficulty of cleaning the siphon.

The siphon, because it is wide and flat, can easily trap air bubbles. Yes, the Aqualifter is supposed to remove them, However if it is clogged, or you get a lot of air bubbles in there at once, the siphon will break

I learned all this the hard way, by actually using an Aqualifter pump with a CPR overflow. I also know others that did the same and had similar problems. It's very easy to end up with floods if you try it, much more so that most other overflows. As you no doubt can tell, I am not a fan of either product, and because of the basic design defects here, I don't recommend their use.


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## [email protected] (Aug 19, 2016)

DaveK said:


> In my opinion, trying to use an Aqualifter pump, especially with a CPR overflow as in your picture is a recipe for disaster. You have several problems here.
> 
> The Aqualifter pump is not that reliable. It often just quits working. This is because it uses a very simple check valve system that is just a couple flaps of rubber. These can fail easily because they can get clogged or they fail to seal. Also due to the small diameter of everything, the pump or tubing easily gets clogged.
> 
> ...


What about pvc overflow?


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## KayakJimW (Aug 12, 2016)

[email protected] said:


> ...I know that sometimes overflows will change displacement for any number of reasons, and from what I understood the difference would just be compensated by the pump in the sump...


Pumps do what they do, and the overflow keeps up with *them*. A pump moves X gallons per hour. If it slows down, so does the water entering the sump because the pump is the source of the flow. The pump creates the flow rate, but it won't adjust itself to an outside source (another pump) helping it. 
Basically, the pump tells the overflow how much water to send through. The overflow does not tell the pump how much to pump.

The problem is having two sources of water propulsion in opposite directions. One doesn't know to keep up with the other. They work independently. Unlike a one pump system** where the in- and out- are both created by one source

And again, just a 1 gallon per hour difference = a 24 gallon per day difference

**or multiple pumps in the same direction. That's why a canister filter return pump can work. Because both pumps are telling the overflow what to do


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## Craigthor (Sep 9, 2007)

HOB Overflow to your sump then return to tank. As long as the pump doesn't pump more GPH than the Overflow can handle you'll never have any problems. I've used Eshopps HOB Overflows recently picked up a Life Reef HOB and the quality is much higher and they can customize certain things if needed which I had done for my rimless tank.


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## DaveK (Jul 10, 2010)

[email protected] said:


> What about pvc overflow?


I'm not quite sure what you are referring to. Here are a few things I have used or built, and my thoughts on them.

In overflows where the long U siphon is removable, I have replaced it with a pair of siphons made from standard PVC pipe and L fittings. I wasn't sure how well they would work, but overall they were not too bad. The downside is that you can't see the inside of the siphon. The up side is that because it's dark in there, you don't get any algae growth inside the siphon.

Most overflows you see being sold are made out of acrylic plastic. For external overflows, that use a siphon, I like Lifereef. You can see then here - prefilter box, siphon box, overflow box, siphon overflow, Eurobrace, Euro-brace, Euro-tank These overflows are not cheep, but you'll only need to buy it once. There are other good overflows out there with similar designs that are also good. 

If you have another product in mind, let me know what it is, and I'll see if I can help.


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## [email protected] (Aug 19, 2016)

DaveK said:


> I'm not quite sure what you are referring to. Here are a few things I have used or built, and my thoughts on them.
> 
> In overflows where the long U siphon is removable, I have replaced it with a pair of siphons made from standard PVC pipe and L fittings. I wasn't sure how well they would work, but overall they were not too bad. The downside is that you can't see the inside of the siphon. The up side is that because it's dark in there, you don't get any algae growth inside the siphon.
> 
> ...


I appreciate this, and everyone that chimed in. 

I ended up ordering a cpr 30 deluxe kit today, as well as a hydor pump, 10 gallon tank and an eshoppes intake tray with filter sock. I also got some plumbing.

All I need now is to research more about a pvc spray return bar.

Thank you again for everyone that lent me knowledge and prevented me from disaster. Very good forum crew here.


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## SingAlongWithTsing (Jun 11, 2015)

[email protected] said:


> I appreciate this, and everyone that chimed in.
> 
> I ended up ordering a cpr 30 deluxe kit today, as well as a hydor pump, 10 gallon tank and an eshoppes intake tray with filter sock. I also got some plumbing.
> 
> ...


make sure you use black air line tubing between the CPR and aqualifter, reduces the chance of algae build up in the tube. also remeber to use a mesh screen in front of the teeth to block some debris.

I ran my CPR 102 w/ the aqualifter for a lil over a year, no flooding or clogging. i only get algae near the weir but it's easy to clean with some paper towels and and some tweezers


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## Bunsen Honeydew (Feb 21, 2017)

DaveK said:


> In my opinion, trying to use an Aqualifter pump, especially with a CPR overflow as in your picture is a recipe for disaster. You have several problems here.
> 
> The Aqualifter pump is not that reliable. It often just quits working. This is because it uses a very simple check valve system that is just a couple flaps of rubber. These can fail easily because they can get clogged or they fail to seal. Also due to the small diameter of everything, the pump or tubing easily gets clogged.
> 
> ...


I wasn't recommending a CPR specifically, it just happened to be the best pic with an aqualifter that I found. Generally, if a HOB overflow builds up bubbles that don't clear, it is because the flow of the pump is not balanced with the overflow. I have used airline and a check valve (with or without the aqualifter) on the commercial HOBs and in DIY PVC ones without problems for about a decade without any problems. I had an aqualifter, but saw it as an unnecessary precaution. I had loaches in the biggest tank, so I didn't have problems with snails, and mine are quite a bit of Najas grass.


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