fishy-fish Posted February 12, 2012 Report Share Posted February 12, 2012 I have a canister filter which is rated at 1200L/hr with no media in it and at tank level. I have three trays of media and the top of the filter is 87cm below the top of the tank where the outlet enters. My outlet hose is also approx 2m long from the canny to the spray bar. Based on this, does anyone know roughly how much preformance is lost? If I was to lift the cannister up 30cm so it's approx 50cm below the top of tank, how much more flow am I likely to get? And the same goes for shortening the outlet distance - would that also help if I dropped it to say a metre? Quote Link to comment Share on other sites More sharing options...
#!CrunchBang Posted February 12, 2012 Report Share Posted February 12, 2012 The higher the pump has to push the water up, the slower the flow rate out. You want the tubes as short as possible to reduce friction and less bends. My aqua one cf1200 has a flow of "1200l/p" but they suggest a real flow rate of 700 - 900l/h in real applications. Quote Link to comment Share on other sites More sharing options...
Ira Posted February 12, 2012 Report Share Posted February 12, 2012 If I was to lift the cannister up 30cm so it's approx 50cm below the top of tank, how much more flow am I likely to get? None. Head height is the distance of the outlet(Spraybar) above the surface of the water in the tank. The cannister's physical location is irrelevant. And the same goes for shortening the outlet distance - would that also help if I dropped it to say a metre? A little bit, that would decrease frictional losses. I don't think it will be much, maybe 50lph. Quote Link to comment Share on other sites More sharing options...
blueether Posted February 12, 2012 Report Share Posted February 12, 2012 I measured my cf1200 at ~650 l/h with full media trays and full length hoses Quote Link to comment Share on other sites More sharing options...
GrahamC Posted February 13, 2012 Report Share Posted February 13, 2012 I believe the rating of a filter is measured with the cannister filter at the same level as the tank. Efficiency drops when the cannister is below the tank due to the increased pressures on the impeller. Quote Link to comment Share on other sites More sharing options...
alanmin4304 Posted February 13, 2012 Report Share Posted February 13, 2012 I always thought that the water siphoned from the tank to the filter and was pumped back up to the tank. Because of this there would be no increase in static head unless it was pumped back to a level higher than the water level in the tank. There will be a slight loss of flow from the friction loss in the pipes but that would not amount to much. I don't think they work unless they are below the level of the tank. Quote Link to comment Share on other sites More sharing options...
b16a2 Posted February 13, 2012 Report Share Posted February 13, 2012 I believe the rating of a filter is measured with the cannister filter at the same level as the tank. Efficiency drops when the cannister is below the tank due to the increased pressures on the impeller. dont know about that one aye, for example pretty sure the eheim classic's for example need to be below the tank as there a gravity fed filter Quote Link to comment Share on other sites More sharing options...
Ira Posted February 13, 2012 Report Share Posted February 13, 2012 I don't think they work unless they are below the level of the tank. They work fine above the tank. Just makes it tough when the filter is empty to siphon out of the tank and fill it. Quote Link to comment Share on other sites More sharing options...
GrahamC Posted February 13, 2012 Report Share Posted February 13, 2012 dont know about that one aye, for example pretty sure the eheim classic's for example need to be below the tank as there a gravity fed filter Just prime them using a gravity siphon below the tank, and then lift them up to where ever you want them to run. Quote Link to comment Share on other sites More sharing options...
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