i have been sat on the fence after reading this about position Dave!

i can see both ideas and that if the filter is higher then its less effort for the pump to return. all pumps have a maximum head and the greater the head = less flow.
and thinking about it once the syphon is started it will be fine aslong as the filter inlet is lower thn the tank outlet. ( am i making any sense?)
And Filter below the tank will make the initial syphon process work easyer ( but only to start)

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