# External filters at the same height as the tank?



## Packers (12 Sep 2011)

Hi,
I'm setting up a new 60l tank.  I live in shared rented accomodation so there are limits to where I can put a tank.  I will be putting it on a currently unused area of kitchen worktop, but this leaves me with serious difficulties with getting an external filter in.  I can't really see how I can put it below the tank without cutting a hole in the worktop, which in a rented house would be a big no-no!  Can an external sit on the worktop next to the tank, or does it need the extra height to function properly?  Also, are there any externals that are small/attractive enough to sit in full view next to the tank without compromising flow?

I currently have a Dennerle external nano filter which can be used at the same height as the aquarium, but I worry about whether this would give enough flow in the tank.  I can't seem to find lph data on this filter.

Many thanks in anticipation!


----------



## Katch (12 Sep 2011)

*Re: External filters - help!*

The flow will be greater with the filter up on the worktop as there is less head (distance travelled vertically).

I see no problem with placing a filter like that.

You might want to consider a HOB filter so its not on show. (Hang on back)

Sent from my HTC Desire using Tapatalk


----------



## cheebs (13 Sep 2011)

*Re: External filters - help!*

I would say, the main disadvantage would be that the filter will be harder to properly bleed. If you have difficulties, see if you can use longer tubes and lower the filter to prime it after a filter clean.

The vertical distance between the tank and the filter will not make a difference to performance. You are correct that head pressure = lifting height, but this is in an open loop (i.e. a pump in a bucket with the outlet not under the water level). IN our tanks we have a closed loop (both input and output are below the water level, and directly effect each other). The siphoning effect pushes water down to the the pump, and back up to the water level of the tank. the olnly lifting the pump itself has to do is from the top of the water level over the tank edge (and even this is negated when the loop is primed and properly bled). This distance doesn't change (other than evaporation) no matter where the pump is placed.

Head pressure is useful in a closed loop though. It can be thought of as the pumps ability to push past an obstruction (elbow, inline heater, crook, etc..) whilst maintaining flow.

Hope thats helpful.


----------



## Packers (13 Sep 2011)

*Re: External filters - help!*

Thanks for your replies guys. 

So it sounds like it might be possible to put an external at the same-ish level as the tank, but I might have more issues getting rid of any air in the system.  Cheebs, you also mentioned that head pressure is useful for getting past elbows/inline heaters etc and I would also have both of these so would that be a problem in a set-up like this?

If I were to consider a HOB filter rather than an external, do you know of any good ones that aren't too expensive?  If I had a HOB I would also presumably have to continue using an internal heater too?

Does anyone know anything about the flow rates of the Dennerle external nano filter, because if that is satisfactory I might be tempted to just use that.


----------



## cheebs (13 Sep 2011)

*Re: External filters - help!*



			
				Packers said:
			
		

> Cheebs, you also mentioned that head pressure is useful for getting past elbows/inline heaters etc and I would also have both of these so would that be a problem in a set-up like this?



You shouldn't have a problem. I was merely trying to explain why head pressure is useful in a closed loop. All pumps should have sufficient head to push past most obstructions used in an aquarium. A pump with a higher head rating will have its overall turnover effected less when restrictions are present, that is all. Don't get worried about it.


----------



## dw1305 (13 Sep 2011)

*Re: External filters - help!*

Hi all,
You have to have a little bit of head, or you get cavitation at the impeller, and the filter always rattles. Could you stand the tank on a thick polystyrene sheet and the filter on the work-top? I've done this and it works fairly well.

cheers Darrel


----------



## Packers (30 Sep 2011)

*Re: External filters - help!*

At the moment I am still using the Dennerle filter with a quoted output of 360l/hr and a koralia nano pump to boost the flow.  Do you think this is sufficient or should I look at getting a new external with more flow (when the bank balance allows!). I've discovered with the filter on the worktop I don't have the necessary height to get a hydor external filter in vertically above it so I'm probably going to have to stick with an internal heater for now.


----------

