Either way will work. You can either insert the seeded foam from the AC
into the fluval, or you can opt to run both filters for about a month. Both of those ways accomplishes the same thing - seeding your new filter.
A venturi is usually used for injecting gas or other liquids into the water flow. This is often used to inject CO2
gas into the water for those of us that run planted tanks and supplement with CO2
. Most users have no need for this feature.