[Larry Hayward]

When you decide to bleach the canvas with a very weak solution, get yourself an inexpensive childs paddling pool (that you can pump up with a foot pump) and fill it with the solution and then soak the canvas pushing it under the water perhaps with a clean broom. Leave in the solution for as long as you feel its working; presumably you experimented on the percentage of bleach and the time it took?

Actually it might be best to get a second pool ready to wash out the bleach from the canvas immediately afterwards, and dispose of the bleach in the other pool 'responsibly'.

I suggest a few washes in clean water to get rid of any remaining bleach.

This job may have to wait to you get a warm day!