# Like canisters in series?



## cale262 (Jul 7, 2008)

I have two RENA XP3's, today I started running them in series on my 90g...Does anyone else run theirs as such? If so, what kinds of media are you running and where?

TIA,

B


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## JWerner2 (Jul 7, 2008)

I do. I run to Magnum 350's in line on some of my tanks.

usually I run one with a micron and switch that to Matrix Carbon once it does its job and the other I leave De*Nitrate in at all times.

Recently I switched the first one with the Micron to filter floss in the canister and scotch brite pads lining the walls of the carbon basket and carbon in the middle.

Of course those ideas probably wont be able to be used by yourself with those filters but gives you a idea. Its cool doing it with 2 cause then the De*Nitrate stays pretty clean and I never need to rinse it off which is good.


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## Ravenatnm (Mar 20, 2008)

Just curious why you would do that. Wouldn't you essentially be cutting your GPH in half, causing less water movement and less filtration? I guess the water that goes through it might be a little cleaner than just going through one filter, but I would think the negatives outwiegh the positives. I also heard that chaining pumps causing early failure due to somthing cause cavitation, although don't ask me to explain it.


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## moneygetter1 (Jan 8, 2006)

:-? Not saying it can't be done cause obviously you're doing it but can't see any long term positives. Turnover is actually half the norm. Suggest passive 'cans' w/ a dedicated pump such as OceanClear or Rainbow Lifeguard for a modular or 'daisychain' setup. Canisters w/ individual pumps were designed to operate seperately. JMPO "T"


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## cale262 (Jul 7, 2008)

Well originally I was trying to cut down on the current in the tank and thought less hose would be nice,...however after some thought I just finnished switching them back, I moved the spray bars to opposite sides to cut the current instead, thanx for the replies... :thumb:


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## JWerner2 (Jul 7, 2008)

The positives are points like mine. One canister can polish the water so that the media in the next lasts longer or if you use media in the second like I do it keeps it from getting dirty and reduces the need to rinse it out which the media that I use does not recommend replacing anyway since its a bio-media. 
I am pretty sure that even in the owners Manual for my Magnum at least ( cant say about the Rena ) it says they can be run that way.


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## nick a (Apr 9, 2004)

Would also suggest a system like moneygetter1 did for series set-ups. Not a fan of double pumps. There are serious potential problems.

What cale262 shows in his pic is something for everyone to keep in the back of their mind, however. That set-up would be almost perfect for using any canister whose motor has crashed as a passive media holder. I would elevate the 1st can and significantly lower the loop to the 2nd so that the gravity drain to the 2nd would be most effective. Mech in 1st/bio in 2nd and the pump on the 2nd (where it would function as the unit was originally designed).


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## moneygetter1 (Jan 8, 2006)

> I am pretty sure that even in the owners Manual for my Magnum at least ( cant say about the Rena ) it says they can be run that way.


 8) Again, not sayin' it can't be done. I can't swear to it but I seriously doubt _*Marineland*_ would sanction the linking of 2 motorized, pressurized units. They possibly might option the 2 filters to be run in tandem (dedicated) but not in series. There is an option for the filter to be linked to a bio-wheel but that's passive (water driven not motor). Double chk. that manual of yours. I understand you're objective & it is a good one but the negatives far out weigh the the positives. The potential damage to one or both motors or at the very least, shortening the life of the motors & possible resulting flood potential is just not worth the 15 min. extra rinsing of the media once or twice a month. JMPO, "T"


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## booba5 (May 3, 2008)

look at it this way, water leaving the first canister (for example) is going 350 GPH, since the second filter would be moving the same, we'd hit a combined speed of 700 gph. That being said, you expect the second impeller to move at that rate of speed? Not only accept 350 gph at the intake, but also INCREASE that speed to 700 GPH? Essentially, you would achieve that 700 gph if you ran them by themselves, if there's to much flow, then make whatever the outlet is bigger, simple as that.

want an anaolgy? could you take 2 car engines and combine the amount of movement? each v8 has 5000 rpm, if you connect them with a bar, will they spin at 10000 rpm? no.


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## bulldogg7 (Mar 3, 2003)

In series they'd still only put out 350 total. You'd have one pumping 350, the other would only be pumping that same 350gph.

In series, once that first filter clogged a little, the second would have to work harder to pull the 350 gph from it that it needs, and the first one would be suffering at the same time. 
It may overheat the motors, not sure how that all works with these motors. But extra heat is never a good thing.


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## moneygetter1 (Jan 8, 2006)

> look at it this way, water leaving the first canister (for example) is going 350 GPH, since the second filter would be moving the same, we'd hit a combined speed of 700 gph. That being said, you expect the second impeller to move at that rate of speed? Not only accept 350 gph at the intake, but also INCREASE that speed to 700 GPH? Essentially, you would achieve that 700 gph if you ran them by themselves, if there's to much flow, then make whatever the outlet is bigger, simple as that.


  Receipe for disaster!! First of all the gph doesn't double in this case. The 2 filters operating *seperately*, depending on media content & packing might yeild 450/500 if you're lucky. In *series*, one negates the other. The contents of the 2 cans are not equal so the pressure is not equal. As dirt, detritus, ect. accumulates it becomes even more unequal. You would have 2 motors trying to move water at different speeds thru each other back into the tank (not good).
As for the car analogy, trust me, you wouldn't want to drive it. I don't want to get into gears & transaxles. :lol: "T"


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## booba5 (May 3, 2008)

I was saying that it wouldn't work, he mentioned that he wanted to cut down on current, so thats why i said make the outlets bigger, so the current isn't rushed in. Also, i know that the media slows it down, i was just breaking it down simply so it'd make more sense lol.


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## kornphlake (Feb 12, 2004)

nick a said:


> I would elevate the 1st can and significantly lower the loop to the 2nd so that the gravity drain to the 2nd would be most effective.


There is no gravity drain, it's a closed loop.


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## nick a (Apr 9, 2004)

Canisters function 1st by gravity drain to the can then by pumping up and back to the tank---it is not designed for suction pull by the impeller. This is why you prime a can--allowing gravity to do it's job first.......


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## kornphlake (Feb 12, 2004)

Gravity will siphon water out when the system is not fully sealed (priming opens a valve to allow air to escape.) Once the system is closed gravity plays no part because there is just as much gravity pushing down on the intake side as there is gravity pushing down on the outflow side. Test it with your cannister, with the intake and outflow both submerged place the cannister on the floor and measure the flow rate, then elevate the cannsiter and measure again, you will see no difference in flow rate, gravity is not a factor. Imagine a 6" piece of tubing submerged in your aquarium vertically, water won't flow from the top of the tube to the bottom of the tube because of gravity, you'd have to physically pump water into the tube to create a current, gravity won't do anything in this case. By the same token you couldn't take a piece of tubing say 24" long with one end near the bottom of the aquarium, start a shiphon into a bucket then plug the end of the tube and place it toward the top of the aquarium and expect it to continue to siphon water and circulate it in the tank, you'd need a pump to get water movement in a closed system.

I won't continue to argue the point, it's something you either understand or you don't. Gravity is irrelevant in a closed system, end of story, get a physics book if you want further clarification or do a google search for hydrodynamics or hydrostatics. A sump is not a closed system, your thought process applies to sumps if that makes you feel any better.


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## nick a (Apr 9, 2004)

Thanks--but don't really need to do much more research--it's what I do for a living.



> Gravity will siphon water out when the system is not fully sealed priming opens a valve to allow air to escape.)


Canister filters are not 'fully closed' systems. Both ends are open. 
No, no valves are necessary to open because once again ----Both ends are open. Priming a canister consists of starting a gravity created siphon flow of fluid to fill the canister.

Once again, gravity fills the can & the impeller/pump unit empties it.

Please consult your canister's manual about min/max distance from can to tank---the reason there is a min is.........



> I won't continue to argue the point, it's something you either understand or you don't


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## bulldogg7 (Mar 3, 2003)

Nick's right, even though pumping water out may cause a vacuum in the intake side, it's still gravity that feeds it. Try raising a canister above the tank and it won't work so good.


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## kornphlake (Feb 12, 2004)

OK


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## moneygetter1 (Jan 8, 2006)

8) Have to agree w/ *nick a* here. If you notice all the canister mfgrs. (A.P., Eheim, Fluval, LifeGuard, O.C. ect.) require placement of their product *BELOW* the base of the aquarium. That's so once the siphon starts, gravity will continue the downward waterflow to fill the 'can' & then plugged in the pump forces water out to make room for more. The faster the water is pumped out, the incoming water is drawn in to fill the void & that cycle continues unless the siphon is broken or the power is cut off. "T"


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