Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
You could remove the media from the 50 a little at a time, perhaps 25% of it each week for a month.
However many fish you have, all the bacteria in the tank and both filters is taking care of the waste.
There is still bacteria living and doing its job in the filter you want to remove.
When you remove that bacteria the remaining bacteria in tank and the new filter must take over. The slower you remove the bacteria (the cycled but old filter) the less chance of an ammonia spike.