How to clean an above ground pool after 2 seasons of non use

[PoolDoc]

We have been backwashing whenever the water coming back into the pool isn't as forceful.

That's reasonable.

But there's no 'quick' way to clean up dead algae in a typical AG pool, because their filters are too small. They manage OK so long nothing is wrong, but not so well for clean up. Where you have 2 seasons worth of swamp, I'd allow 2 weeks for clean up.