# Canister filters and flow



## kilnakorr (13 Apr 2020)

I cannot seem to get a decent flow through a canister filter, and I've tried quite a few models over the years.
My main problems are the limit in hose size and all the inline equipment.

How many of you have tried running an external pump through a canister filter(impeller removed from filter), and what flowrate was used?


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## Aqua sobriquet (13 Apr 2020)

It’s an interesting idea but I would expect that some research has determined the optimum flow for a given canister size with expected media? If you increase the flow massively I wonder if it will clog more quickly? Ok I suppose if you don’t mind cleaning it out more often? If the canister filter you have is operating correctly in all other respects perhaps you could just use a power head in the tank to give greater water movement? Just a thought.


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## kilnakorr (13 Apr 2020)

Aqua sobriquet said:


> It’s an interesting idea but I would expect that some research has determined the optimum flow for a given canister size with expected media?


I agree to some extend.
The problem is, they are never designed for inline equipment. After adding a reactor, inline heater, uv etc. the flow has been cut significantly. Being a more powerful filter you'll get a much bigger canister that isn't needed. Hose size/diameter also increases and finding inline equipment that matches is virtually impossible.
I already run powerheads since a spraybar isn't and option as flow is already low.


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## dw1305 (13 Apr 2020)

Hi all, 





Aqua sobriquet said:


> If the canister filter you have is operating correctly in all other respects perhaps you could just use a power head in the tank to give greater water movement?


That one. 

Also if you reduce the head (vertical distance between the filter and tank) you get a lot more flow. 

cheers Darrel


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## kilnakorr (13 Apr 2020)

dw1305 said:


> Hi all, That one.
> 
> Also if you reduce the head (vertical distance between the filter and tank) you get a lot more flow.
> 
> cheers Darrel


Not possible. The head pressure is the problem, as the line has equipment which increases the total lenght and head.

The filter is built for certain flow, and so is much of the equipment attached inline. Reducing this flow then neither filter or equipment runs as it should.
Currently running a 2000 L/hr filter but estimate flow to be around 500 L/hr or less.


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## Millns84 (13 Apr 2020)

What inline equipment are you using? I use prefilter canisters on two of my filters and found that the flow was much better if they were fed from the top down.

In terms of plumbing in an extra pump, it is possible with the likes of the Aquael Unipump (external motor which the Maxi Kani models use). You could either supplement your current filter's motor or use a more powerful pump altogether. 

There's also an element of "torque" to consider. You won't necessarily have to go out and buy a 5000lph inline pump, as supplementing your current filter's pump with another would help to overcome the head pressure and get better flow. The only thing to consider with this option is matching the pumps as you could potentially strain one. 

It helps to think of pump motors as a car engine and everything between the inlet and outlet of the filter as weight in a car - increase the weight, slow the car down. You can either reduce the weight or increase the power of the motor to get better results


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## Aqua sobriquet (13 Apr 2020)

Ah I can see the problem now with inline equipment. Do any manufacturers make a filter with built in heater and UV I wonder?

I’m just setting up a new Nano and the filter has built in UV and I’m using an under tank heater so I’m hoping flow will be ok.

Let us know how you get on if you decide to use an external pump.


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## Zeus. (13 Apr 2020)

Use to have two spraybars one ran off an FX6 and other ran off an independant Eheim 3000+ and it worked well apart from maintenance, plus spray bars was ugly, so went for Maxspect Gyres x2 and did away with spraybars and never looked back


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## Millns84 (13 Apr 2020)

I'm going to show my filter geek level here but... Boyu DGN filters have 200w heaters and an optional 5w UV all built into the bottom of the canister. They're pretty cool filters, you can even electronically adjust the pump's flow rate.[


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## kilnakorr (13 Apr 2020)

Thanks for all the replies and ideas.
To explain further, I have a closed top tank with holes in the bottom. These holes and pipes already limits the diameter of the filter I can hook up. FX6 or similar won't fit any equipment and won't fit under the lid anyway.


Millns84 said:


> What inline equipment are you using? I use prefilter canisters on two of my filters and found that the flow was much better if they were fed from the top down.
> 
> In terms of plumbing in an extra pump, it is possible with the likes of the Aquael Unipump (external motor which the Maxi Kani models use). You could either supplement your current filter's motor or use a more powerful pump altogether.


I'm currently running: filter, reactor 1, reactor 2, uv, tank. Removed the heater as the uv and light already heat up the tank pretty good.
The Aquael Uni pumps aren't powerful enough.
Running both filter motor and external comes with problems. Finding right size won't be easy and if one of them breaks down, the other won't be happy.


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## kilnakorr (13 Apr 2020)

Millns84 said:


> I'm going to show my filter geek level here but... Boyu DGN filters have 200w heaters and an optional 5w UV all built into the bottom of the canister. They're pretty cool filters, you can even electronically adjust the pump's flow rate.[


Just took a look at them. What I REALLY like is the various sizes has same flowrate! I don't need 25 L media in my planted tank!
The uv is useless at 5w (and who knows the actual dwell time and effect). Can't find info on hose size though.


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## Millns84 (13 Apr 2020)

kilnakorr said:


> The uv is useless at 5w (and who knows the actual dwell time and effect). Can't find info on hose size though.



I think it's more of a clarifier at that wattage, certainly enough to take care of waterborne algae but not much chance against the likes of ich etc.


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## kilnakorr (13 Apr 2020)

I noticed a possibility to not restrict the flow as much, but unsure about the math behind it.
With reduced pipe diameter flow is restricted. But will a bigger diameter on some of the line have an effect? Lets say only the last foot or so would be a smaller pipe diameter?


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