Will it affect the main one?? I don't desperately need it right now as all my fish are juveniles, just thinking ahead as my Angels are growing quickly.
In that case will be fine mate wash the media and in it goes, after 8 weeks or each filter will be doing approx 50% of the work of the whole tank, if you ever need to remove the a filter for another tank instant cycled filter you just go easy on feeding for a week until both filter catch back up to 100% of the work for their own tank