# boosting flow of an eheim external using a pump



## Skatersav (29 Aug 2012)

Ladies and gents,

Quick question:

Would there be any harm in adding a water pump (maybe a pond pump or something) to the return of an external canister filter (eheim, to be precise)?  I have a big tank, high energy, and need lots of flow but don't think the current set up really works.  I think I have seen someone put a pump in line with an external filter but I can't find where...

Thanks in advance,

Sav


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## chilled84 (29 Aug 2012)

Why attach it inline? If your going to get another pump, use the extra flow unatached elsewhere within the tank. Thatll help your flow problems better than on single diy powerfull outlet. Hope that helps. Cheers.


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## geoffbark (29 Aug 2012)

That was me. On the Barr report. I run a pump inline from my eheim. 

http://www.barrreport.com/showthread.php/9937-Has-anybody-done-this

Don't use the eheim pump at same time.


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## geoffbark (29 Aug 2012)

chilled84 said:
			
		

> Why attach it inline? If your going to get another pump, use the extra flow unatached elsewhere within the tank. Thatll help your flow problems better than on single diy powerfull outlet. Hope that helps. Cheers.




To minamise items in the tank, i only wanted one inlet and one outlet pipes.


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## ian_m (29 Aug 2012)

Skatersav said:
			
		

> Would there be any harm in adding a water pump (maybe a pond pump or something) to the return of an external canister filter (eheim, to be precise)?  I have a big tank, high energy, and need lots of flow but don't think the current set up really works.  I think I have seen someone put a pump in line with an external filter but I can't find where...


Not a done thing two pumps in series. If the second pump, for instance, is a slower flow rate than you canister pump, then it will end up slowing the whole system down (or being overdriven by the more powerful pump).

You really only should have one pump per water circuit loop.

What about a wavemaker to increase flow/circulation around the tank ?

Some people, with large tanks, have one loop of just canister filter and another loop of pump, hydor inline heater and CO2 diffuser.


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## ceg4048 (29 Aug 2012)

Skatersav said:
			
		

> Would there be any harm in adding a water pump (maybe a pond pump or something) to the return of an external canister filter (eheim, to be precise)?  I have a big tank, high energy, and need lots of flow but don't think the current set up really works.  I think I have seen someone put a pump in line with an external filter but I can't find where...


Hi,
   You have several options. It is possible to run two pumps in series but the specifications of the pumps ought to be considered. Normally, you want the second pump to be the much stronger pump so that the filter pump acts only as a "feed" pump and the second stronger pump is the "boost" pump. This works well when the the height of the the tank is large (or if the pipe runs are very long causing frictional losses) and when the first pump is not strong enough to do the job properly, so it just delivers enough flow to the second pump to make life easier for that second pump. If the two pump outputs are similar then you tend to flood the second pump and you loose efficiency.

As mentioned in the link, you can also disable the filter's pump by simply unplugging the unit and removing the impeller. In that case it would probably be better to have the boost pump before the filter so that you push the water through the filter instead of pulling it through. Much fewer complications that way and probably easier to prime the pump. I actually like this option much more for improving flow than the method of adding powerpacks, or powerheads to the inside of the tank, because all that flow is going through the filter instead of just being recirculated and now, since it is all going through the filter pipework the flow stream is much easier to control
and to manipulate with a spraybar which you can now elongate to cover the entire distance along the tank without having the flow peter out.

Try both options and see which works better.

Cheers,


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## Skatersav (29 Aug 2012)

Thanks everybody.  I appreciate the responses greatly.  I'm sure you all have more important things to do than educate me - I'll have a go at implementing the suggestions and let you know how it goes.  I'll do a before and after and all that stuff.  Cheers.  S


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## ian_m (30 Aug 2012)

Could always boost flow/circulation like this. Maybe fit another spray bar on outlet.


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## fleabilly (11 Dec 2012)

What about adding the second pump to be a needle wheel co2 diffuser?
I am running a eheim 2217 out a 80cm spraybar on the back. The flow is just about enough. But I wanted some type of inline co2 plus was contemplating an inline purigen reactor down the line, and I have been researching adding a pump I to the water loop.


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