upflow waterfall filter

[justin case]

So I'm building a small pond in my back yard. Like a couple hundred gallons. The thing is I'm trying to do it as cheaply as I can. So I decided to build my own waterfall box. I decided on an upflow design but was wondering if it would be helpful if I were to put an aurstone in the bottom so the bacteria have some extra o2. What does everybody think? I'll have a prefilter for mechanical and use lava rock for bio. Any input is apreciated. I'll post pics later.

 

[Cory]

An airstone wouldn't hurt. But in theory you shouldn't need one, as you're feeding water from the pond. If there isn't enough oxygen coming in from that you've got bigger problems.

 

[justin case]

I figured but I thought more can't hurt. But now that I built it I'm finding that I'll have to either cut the lid or leave it off because the air is messing with the outflow a little.