Doing super frequent water changes.. what can go wrong?

[kien]

I want to try an experiment and was wondering about a couple of things. What i want to do is try to achieve an ULNS by doing very frequent water changes. Like, i'm talking 10% every 2 to 3 days. I have a 150g system so that's 15g every 2 to 3 days. What I'm wondering is what will be the fallout? I suspect the natural fauna of the tank could be diminished, but enough to be a problem? Has anyone ever tried this? Searching through the forums it seems the average minimum is about a week for a water change. My logic is that the natural ocean works well because it is highly diluted. Well, I figure if I inject new saltwater very frequently then I could nearly achieve this. So what's wrong with this logic?