If you "feel like you're backwashing all teh time", should that not be an indication that your sand IS in fact doing it's job?
I'd worry if I DIDN'T have to backwash......
You should backwash when your pressure changes by about 5 lbs.
If you want to get your water crystal clear, you may have to do teh following:
First off, get the algae out and the pool vac'd clean as you can, if the water is foggy/dull, put in some clarifier or floculant - this essentially bunches the fine particles that the filter is unable to get individually. This doesn't always help get them out, but it does drop them to the bottom, to get them out, put 1-2 cups of DE into the skimmer, wait 5 minutes - pressure should rise 3 lbs, then vacuum the pool. With DE you will need to backwash about twice as much as without.