dried on algea

[grammy57]

We are taking down our Intex pool for the winter. We were unexpectedly gone for the last part of summer so we had a bad algea problem. We drained the water and now have green stuff dried on the sides and bottom. We have used bleach water and a scrub brush but it isn't coming off very well. What can we use? What will happen if we just fold it up and store it for the winter?
thanks for your help.