I'm gonna be building a filter soon. nothing major, just some HOB style filter that'll hopefully do 1000 gallons per hour. anyways, ive read that BB need oxygen to survive, so i'm wondering if i should put a small airstone at the bottom of my filter so that it goes up through the foam filter and whatnots? will this actually do anything for the BB? if i do this, could i not put an airstone in the tank since the airstone in the filter will also aerate the water? any comments or suggestions are welcome.

An airstone in the filter is not going to give you more air in the tank. It's a nice idea but the oxygen that fish need has to be dissolved in the tank water to be accessible. So putting an airstone actually inside the filter will be good for the bacteria growing there but will not be giving extra air to the fish. If you have a high powered motor- like you say 1000gallons turnover -the splash from the out tube will create plenty of air in the tank water if it slightly above water level. Its the combo of the air and the splash mix that dissolves the oxygen into the water underrneath making it usable for the fish..with this kind of splash you can probably do without an airstone in the tank. Bear in mind that even with a strong splash from your filter outtube (so you can see bubbles actually shooting down intoi the water) its adviasable to have extra air when medicating or when the temperature is higher
Cool- making your own filter.