wow thats one fuzzy tank... i would kill to have a big tank, it makes me sad to see somone waste a tank like that... i check on my 10 gallon every 15 min!
Don't laugh, I can guarantee someone here will get in a similar problem too at some point. That's about a months solid growth I'd guess, and I bet his phospahe and nitrate read zero too....
I would still bet that is only a couple of weeks uncontrolled growth. It's at the point it will be break down time to fix it though, or get the rocks out and scrub them.