Seeding sponge filters

I've recently purchased a few sponge filters for my new quarantine/growout/hospital/whatever tanks. I had planned on just putting them into the tanks and then beginning the cycle on the tanks and allowing the filters to mature naturally. Then, as I was reading the instructions for the filter it mentioned to put them in an established tank for a few hours prior to installing them in their new home. I thought to myself, "Self, why didn't you think of that?" So, I put them in my sump for now.

My question is: how long should I leave them in the sump? The box says a few hours. Is that enough? They've been in there about 15 hours now.

Thanks,
Jonathan

 

I have at least one in my sump at all times so I can set my QT up at a moments notice whenever the need arises. A few hours is not going to give you much bacteria growth.

 

+1 to ^^.