# Filter inlet and outlet positions on a 125



## Diana (Jan 14, 2010)

I think you are mixing up the flow, and will not get good circulation by aiming all the spray bars in different directions. 

Set them up to all aim the same way. 
Example:
If all the spray bars are lined up across the back-top, aimed at the front, then the intakes are near the bottom-back, perhaps one in each corner. This would give you the traditional water movement that is typical. 
Example:
If all the outlets are concentrated at one end, and all the inlets at the other end you would have a river tank. 

If you have any kind of water pump, some tubing and some Tees, set up a few arrangements in a smaller container (perhaps a plastic storage container, or another tank) then test the water movement like this:
Use a chopstick or shish-ka-bob skewer. Tie thread onto it in several locations. Leave several inches hanging. Then stick this skewer into the water flow in many areas and watch what the thread does. 
Add some food coloring, or some fish food that sinks slowly (most flakes are OK, and large enough to see)

If the threads pretty much all flow in one direction, this is good. If the food coloring and fish food show a smooth flow, this is good. 
If any of these show swirling, cross paths of water this will only get worse when you add hardscape and plants. Not a good way of setting up the water movement. You want a pretty strong flow going toward the filter inlets so the debris gets carried there. Most debris is heavier and has a tendency to fall out of the water column if there is any cross currents. 

Get a pretty good idea of what is going on with the miniature set up, then, when you build the tank and it will hold water try this again with the actual filters you intend to use. Fine tune the placement by adding any sort of rock to represent the hardscape. 
Once the plants are in you still might have to add a power head aimed at some hidden corner but it will be a small one.


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## aclaar877 (Feb 19, 2014)

I have been brainstorming ways to improve circulation in my 155 with two canisters and one Koralia. I had a similar setup to yours, but with vertical spray bars on the back wall. Last week I changed mine to aim for a single circular motion and results are better. I have both inlets at lower left. Next to them is one spray bar pointing right, with bottom elbow angled ever so slightly at midground plants on left side. Halfway across the back is second spraybar, pointed the same way. At top right is my Koralia pump, sending water down and across the foreground plants toward the two inlets. Weakness - flow is very small at front left corner, and flow appears low at inlets so I don't think the debris is getting to the inlets as well as Diana recommends. But, almost every plant has some visible movement, and this is even with some huge driftwood with large java fern near the back middle of the tank. Clear improvement on what I was doing, where I had an inlet in the middle. For a couple days I also tried Diana's second example above, where inlets were in lower left and all water pushed from right to left. My current setup appears better. A guy on the Barr Report website has a nice 180, and he puts spraybars horizontally on the top left and right sides, aimed at each other, and inlets at bottom R/L corners.


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## laconic (Oct 7, 2013)

I have a 120G with 2 eheims. On is on the left side and the other on the right. Spray bars are just below the surface pointing upwards. I have nothing on the back.


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## aclaar877 (Feb 19, 2014)

laconic said:


> I have a 120G with 2 eheims. On is on the left side and the other on the right. Spray bars are just below the surface pointing upwards. I have nothing on the back.


How is your flow on the bottom front corners? I'm considering trying that setup.


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## Diana (Jan 14, 2010)

In a tank as large as a 180 I would think that any one filter would not really do the job anyway, so two, set opposite each other, are not really in conflict. 
This will vary with the size and shape of the tank and the flow rate of the filter, I am sure. 

Good to hear about how different arrangements are working. 

Seeing the plants gently moving, and seeing the debris getting removed are both good signs. 
A spot that accumulates debris suggests that some change needs to happen.


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## tylergvolk (Jun 17, 2012)

I am setting up a 125 soon as well.

I have Eheim 2217 and 2 Eheim 2213 to work with. Any suggestions?


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## laconic (Oct 7, 2013)

aclaar877 said:


> How is your flow on the bottom front corners? I'm considering trying that setup.


On the left side, the intake is on the front and on the right side, the intake is on the back. I added a hydor circulation pump on the right as well because the eheim I have there is a smaller model than the one on the left.

Circulation seems to be good.


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## Briggadane (Apr 28, 2014)

I think it depends on that fish you have in a tank. Some might prefer a good current, so flow should all move one direction. If any fish need a calm area, filter on each end pointed toward the center of the tank work best( my preference, for my 125).
I also stagger the filter outlet depths. One is set to gravel level, one is 5 inches from the surface. I also keep a powerhead with filter attachment in the corner. Filter center is equal to tank center. 
Looking at my tank, the first filter is 1 foot from the left end, the second filter is 1 foot from the center brace to the right. The powerhead is in the right back corner, and my uv sanitizer with slow flow powerhead is in the right front corner. You'd think I have some serious water flow issues, but not so. Everything is positioned to cause interrupted flow, and it works. 
It also keeps a very steady temperature throughout the tank.


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## tylergvolk (Jun 17, 2012)

After doing some research, I've found that is depends on several things. Your decision should dictate what you want to accomplish.

For example, if you goal is high tech then you may need more flow to distribute co2 but don't mistake this for filtration. They are two different things. 

Looking for more flow? Than a power head is the cheaper way to go. Looking for more filtration for a higher fish load? Might wanna get a bigger filter. Looking in for both? Get a bigger filter with a higher gph.

My goals are low tech plant variety with no co2. With that said, I'm sure my two canister filers should be enough flow but maybe not enough filtration because I haven't decided on my fish load yet. However, I plant to plant very heavily and the plants do there part in filtering as well.


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## johnclarke (Jan 4, 2018)

Wonderfully simple answer 
1. Get half a dozen small grassy plants in pots arrange them on the bottom in the pots. if you observe gentle flow, you're half way there, you know you have gentle flow down below.
2. Effective oxygen exchange is mostly at the surface so ensure you outlet water from the filter causes some rippling (not splashing). not sure you need , or want to spray. i have naturally warm ambient temperatures and everyone behaves happily. clearly well oxygenated.
3. I found aiming across the tank from a corner filter at about 30 -45 Degrees and pointing upward enough to cause a good ripple, kept the fish very happy, with differing flow rates attracting different fish, and therefore (partially) segregating species such as Danios and Rasboras, while the tetras happily flit around below, and Barbs flit around blissfully.
All sleep comfortably.


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