1)Calculate actual pond volume

Pond shape	(metres)	x	(metres)	x	(metres)	x		=	Volume in litres
Circular Ponds	Diameter	x	Diameter	x	Average Depth	x	785	=	Volume in litres
Rectangular Ponds	Length	x	Width	x	Average Depth	x	1000	=	Volume in litres
Odd shaped Ponds	Average Length	x	Average Width	x	Average Depth	x	800	=	Volume in litres
Triangular Ponds	Length	x	Width	x	Average Depth (divided by 2)	x	1000	=	Volume in litres
Example A rectangular pond is 4 metres long by 3 metres wide and 70cm average depth	4	x	3	x	0.7	x	1000	=	8,400 litres

Next step is to convert actual volume to our base starting point.
Because basic pond circulation is based on a near natural garden ponds with plant zones, without fish you should take the actual volume and divide by 2, to give a pond circulation of once every two hours

So armed with a figure representing 50% of the actual volume, simply add the following additions.