Are you talking filtration for the entire spawning and rearing process?
If so, my method is broken down into three methods -
1.) For the initial spawning and first week, I do not filter the water. I add hardy plants such as Anacharis and fern, which help to filter the water on their own. Filter currents (even from the most gentle filters) can be very destructive.
2.) At the one week to two week point, I turn on a previously submerged sponge filter with a control valve connected to it. These are dirt cheap, you can find them for around $4 on eBay. Depending on the size of the spawn and what I've spawned them in, I also begin using an airline tube with a piece of pantyhose taped to the end of it to remove poo and debris, while keeping the kiddos safe.
3.) Once the fry reach approximately an inch in size, I increase the amount of filtration to what they can handle. Keep in mind that the current normal waterfall filters create can throw the babies around enough to do serious damage, or even kill them.
I also add mystery snails at night as a clean-up crew to remove uneaten food. Remember that snails create waste, too, so it'll still need to be siphoned out. They just get the hard-to-reach places :)
Here's a link to the type of sponge filter I swear by -