# best configuration for dual canister filters?



## fishyface (Feb 7, 2005)

my plan is to set up a fairly heavily planted 75g tank and i was thinkin 2 rena xp2's for circulation and filtration. am i best to run them separately or in series? are there any other better ways i configure this? one of these will have a rex reactor setup on the output side...

i value and appreciate all input! thanks,
darryl


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## stuckintexas (Aug 12, 2008)

i would think that the 2 filters would work best if run independent. maybe have each one to run on opposite sides of the tank.


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## niko (Jan 28, 2004)

Run them separately. But cross the inflow and outflow:

The inflow of filter1 sucks water from the left. The outflow of filter 1 discharges the water in the right side of the tank.

The inflow of filter2 sucks water from the right. The outflow of filter 1 discharges the water in the left side of the tank.

--Nikolay


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## dogdoc (Feb 3, 2006)

I would go with at least XP3's or even XP4s. Especially if you are going to have a heavily planted tank. I have two XP3's on my 75. I also have a powerhead and a Koralia 2 to provide extra flow.

I think the XP2's might be a little underpowered for a tank that size. Especially if you are going to be driving other equipment with them.

The XP4's weren't around when I set things up or I probably would have had two of those.


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## rich815 (Jun 27, 2007)

niko said:


> Run them separately. But cross the inflow and outflow:
> 
> The inflow of filter1 sucks water from the left. The outflow of filter 1 discharges the water in the right side of the tank.
> 
> ...


+1 on this advice.

I have two Eheims on my fairly heavily planted 72 gal (see "My Tank" link in my signature). I am running them independently. A 2026 with an inline PVC CO2 reactor on the outflow and a 2028. Only difference to above is I have the 2026 output spray bar across the middle of the back with three holes in the output spray bar pointing across the top middle (back to front) of the tank, three holes pointed down against the back glass, and I drilled one hole in the elbow to spray to the left (facing tank left), this way to disperse the CO2 enriched water about better in three directions. The output spray bar of the 2028 is on the left side spraying mostly across the tank left to right (and mixing the main 3-hole output from the 2026 CO2 outflow water) and one 3-hole section pointing down. I also have a Koralia 2 on the left side, sort of towards the back, pointed to the right front corner. Until I did all this I was getting patches of BBA from time to time even though my CO2 drop checkers were a nice lime green. Since being over-the-top in my efforts for large dispersement the BBA has dropped off for just the occasional tuft here or there (easily treated with H202 or Excel) and I attribute this to better CO2 dispersement around the tank.

I was just given a used but working XP3 and plan to add that too since I am fairly heavy on the fish load and I really do not see how "over-filtering" would be an issue. Some people recommend in filtering to go 10x the manufacturer's rated pump output vs. your tank's gallon size (not flow).

I'd consider at least one of your Rena's be an XP3 if not both. It will not hurt.


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## fishyface (Feb 7, 2005)

great advice by all, thank you. i will do what you've all suggested here folks and as for the xp2's...they're still boxed and will be exchanged for xp3's today! just out of curiosity Nikolay, what's the difference in whether the input/outputs are crossed it they're the same filters and flow rates? 

thanks,
darryl


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## greenjoe (Jan 14, 2006)

I think it has to do with the water circulation/movement in the tank. Water from one side is circulated to the other side.


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## Logan's Daddy (May 3, 2008)

greenjoe said:


> I think it has to do with the water circulation/movement in the tank. Water from one side is circulated to the other side.


+1

Crossing the inflow / outflow will provide the most consistent water throughout the tank. Co2 and fertilizer will be distributed very evenly throughout.


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## fishyface (Feb 7, 2005)

thanks guys! i've gone ahead and set up as suggested!


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