What size pump do ypu need for a 65000L pool?

That's not so easy to answer with a LOT of other information. You need a pump big enough to run your filter, your cleaner and anything else you have. Without knowing if your pool is salt or chlorine, what kind of filtration you are running, how many trees you have, etc. it simply isn't possible to give you a useful answer.

In order to get accurate information for YOU, contact some reputable pool service dealers and installers in your area. They will be able to look at what you have going on and give you an answer that works.