Switching to Matala gravity filter from an in pond filter how long to run both?

[Bossman]

I have an 800 gallon above ground pound. I have been using an in pond filter but find that to clean it there is too much mess gets in the pond. I am changing to a Matala above water gravity feed system. I have just finished setting up the Matala filter. Today I have both filters running. Does anyone have any idea how long I will need the in pond filter until the Matala filter will be able to take over the biological needs of the pond and I can remove the in pond filter.

 

[mrsclem]

Can you remove the media from the old filter and put in the new one?