To start I would change out 50% a day in two 25% changes. These can be one right after the other.
Test your water every day before the change. As soon as the water condition improves to 0 ammonia, 0 nitrite, and 10-20 nitrate, you can slow the changes down to maintain that condition.
What size tank are these fish being housed in now? You have enough fish there to require 300 or more gallons. Is there any way you can re home one of the plecos? If you keep up with the water changes your algae shouldn't be a bad problem, and they add huge bio load to the tank, ALL these fish are messy, but a pleco might be easier to find a new home for.
Good job on the rescue!
