Bleach water sprayed on should do it and won't harm the critters as it is very quickly broken down.

use the outdoor clorox.....gel like clorox, used it when we pressure cleaned the house and painted, plants were fine....follow the directions........

I have found that borax (20 mule team at the laundry section of your store) works fantastic.

Our wooden deck had gotten quite slippery. I put the borax in a strainer and sprinkled it over the slime. Within 18 hours it was no longer slippery and it lasted for at least 10 weeks.

Pretty sure borax is much less toxic than bleach.

I sprinkled some diluted bleach on the slime yesterday with a watering can, but then we had a downpour, so it probably washed it away. I'll try the borax, but it's supposed to rain here till sunday, so I'm not sure anything will work right now. This stuff is a good half inch thick, a lot like seaweed, not the thin slimey patches you can get on a deck or walkway.

Bayer makes a moss and algae killer that works wonderful

It sounds like Nostoc cyanobacteria. Try spraying liquid copper on it if bleach didn't work. I also have some of it at my place.

slime everywhere here....once the temps break...bring out the pressure cleaner :)...m