Ceder Fence Staining? We had our wall changed last year to a ceder barrier....

We had our wall changed last year to a ceder barrier. We started to stain it but then the weather get cold and we did not finish. So now we considered necessary to finsish it. I guess i have to rent a pressure washer so that i dry-clean it first. But what am i aiming to clean though i dont see anything dirty!!
Also which do i rent:
Pressure Washer 1,000 psi (Electric)
Pressure Washer 2,000 psi (Gas)
Pressure Washer 3,000 psi (Gas)
Pressure Washer 4,000 psi (Gas)

Thanks

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Answers:    merely been a yr so can't be that dirty ...unless there's any dirt at the bottom of the paling from dirt being splashed up from the rainfall I wouldn't bother power washing.ceder is a soft would...I wouldn't use more the 1000 psi to verbs it off

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