Will I regret an uphill drain pipe?

I'm about to start excavating a pond 4' deep with a 55 gal drum filter
(drums 3' high; jj's design). One nagging doubt I have is about the
pipe from the bottom drain to the filter. It'll have to run uphill at
least 1.5' in order to enter the filter. Seems to me that with enough
flow I shouldn't have problems with the pipe clogging, but I'd feel
better about it if the pipe ran down rather than up.

I've considered constructing an extra deep drum from two drums so the
bottom of the drum is below the bottom of the pond, but perhaps this
isn't necessary.

Any opinions?

Chris