Make sure you put a sponge of some sort over the filter. Other wise the babies will get sucked up.
I use the foam blocks and put a slit in the middle with scissors. Then I slide that up over the filter intake.
Try to get the thickest foam block you can. I know that I get the 1 inch last time, so 2 in a box and it is doable but i would prefer the 2 inch one instead.
Or you can get an actual sponge filter.
It is also great for additional bio media and a place for the shrimp to feed.