When a pool has been green for a long time - more than 6 months - the interior is coated with a green algae slime that is often crusted onto the pool interior. To remove it, you can complete a pressure wash, acid wash, or chlorine bath. In most cases, an initial pressure wash removes most of the algae slime. I'm posting photos of a recent job showing an interior pressure wash and the results.
Pool is drained... and stained.
The spa is pretty dirty too!
Beginning to pressure wash.
And more washing...
And still more pressure washing...inch by inch. This job took us about three hours.
Crystal clear again!
Here's the final picture!