Try using thick trash bags etc, cheap and big.

Turn off CO2, increase surface turn over, do 50% before and after
water changes and you should not need more than 3-5 days to beat it
back pretty good. Some algae will not be affected much, most will.
Trim off any left overs, dose well and keep dosing in the future/keep
the CO2 high etc.

Regards,
Tom Barr