Don't put anything from that tank into yours!
She doesn't need to scrub it all out, just get rid of the algae/bacteria and find the cause. She need to remove as much as possible, physically, and siphone the gravel well. Clean off all ornaments and plants then try blacking out the tank for 3 - 5 days. No feeding the fish during this time. They will be fine without food and in the dark.
If this doesn't work, try the Furan 2. Erythromycin is a prescription only medicine whereas Furan 2 can be bought from the pet shop.