Hi tetraman
Your tank won't need the power filter since the fry are so small at first that they produce little waste. Once the adult corys have spawned and you take them out, you can use the filter, with it's beneficial bacteria, somewhere else.
What you can do for the fry is get a small air pump to first run the airstone(s) to keep the water circulating around the eggs, then switch it to a sponge filter like this one.
http/www.petsforum.com/ATI/atb100.htm
They are good to grow beneficial bacteria on and microscopic creatures will also grow on there which your fry will eat as snacks. There are other brands on the market, but you might have to go to an independent lfs to find them, or order them online. The important thing is that they cannot suck the fry in like other filters can.
When they get larger still, you can add a divider on the air line and run a box filter too, for both biological and mechanical filtration.
Of course, since you will then have an extra filter full of all that beneficial bacteria, you can always set up another tank. This could be the start of MTS.