not quite sure which filters you're talking about. but if you're growing larvae or fish fry then you dont really need a filter due to the fact that virtually every filter will suck any tiny animal you have. when i was growing fish fry i just put them all into a 12 gallon tank with a heater, a live rock, light and airstone to keep things moving. and just perform a small water change once a month. larvae usually wont produce much waste.