Upgrading a filter

[Hoovercat]

Hey guys, I installed a Magnum H. O. T. on my 29 gal. yesterday. How long should I leave my old Penguin 150 running along with it to avoid a spike. I figured 2 weeks but 400 gph (250 mag +150 penguin) seems like a LOT of flow so I'd like to remove the old filter ASAP.

 

[Husmut]

If it were me I would throw some of the filter material in from the old one, give it a day or so to start growing in the new one and get rid of the other. 2-3 days. But thats just me . Im a little impatient!