Diluted bleach should do it, 4-1 is my usual mix for something like that, our back steps get slippery too, I have to do that about once a year usually. If you spritz it on with a spray bottle, it should just dry up without washing into anything, but I've never had diluted bleach bother any plant, I clean stuff with it in the yard often. On bricks, it would just evaporate quickly, as bleach does. If it's really bad, you can scrub it with a janitor broom while wet with the diluted bleach, but probably/hopefully not necessary.

But are you SURE you're sure about the plants? I've got some stuff it would KILL me to lose.
Maybe I should pout it in a paint tray and roll it on?
AAMOF, if rolling on, could I just use round-up?

You're talking about algae/mildew, right?

If you have some cardboard or even sheets of plywood laying around, use them to 'edge' your patio while you spray the bricks to prevent over-spray from landing on other plants in the area. Tarps or old sheets would work too, though the old sheets could still soak through and affect plants if they're not removed immediately after spraying.

Paint the bricks with a grit additive (available anywhere paint is sold). That will create traction, even when wet. The deck of the patrol boat was painted with this way when I was in the Coast Guard. This is an especially good solution if there are stubborn stains on the bricks that won't go away. However, it does make bare feet walking a little touchy, and you'll have to repaint every few years.

Bleach is about the only thing that works. All of the commercial washes are basically bleach and detergent. I've used a fair number of concoctions and mixing your own is just as effective as buying something. Bleach will damage sensitive plants. You can mitigate that by wetting down adjacent plants before application. A pressure sprayer set for a very coarse spray and operated at low pressure will reduce splatter. Leave it on for at least an hour. Scrubbing with a brush helps. Spray lots of water on the adjacent vegetation when you rinse the bricks. You still run a risk the first time. You could also set up a cardboard shield for the more valuable plants. I lived North of Seattle for 25 years. Cleaning the slimy green glow from decks and the North side of the house was a frequent chore. I never lost a plant, but we didn't have all this tropical stuff up there. We haven't had much problem with slime down here.

... or you could try throwing a lot of sand on the walk.

Larry

My parents have this problem on the concrete pation under the crape myrtles and they just hit it with the pressure washer from time to time.

Thinking another non-chemical approach might be a good scrubbing w/ a stiff brush - maybe a wire brush - maybe w/ some detergent?

Sorry,,, been offline all day...

Yes, I'm talking about algae/mildew/moss.

My patio is surrounded w/ aloe, coleus, begonia, camellia, gardenia, Durante, amaryllis, and daylily.

The bricks are sorta sand set... Sand and concrete mix... But kept on the softer side (mistake.., don't listen to other Pinteresters) Anyway, it's really too big to "edge"with anything since I don't have enough of it to do the whole thing. IS there a reason I couldn't roll it on? Is that a mistake?

I can't pressure wash as Purpla (lol) noted. I've got so much Artillery Fern in the cracks and holes, I could spit! I'm looking for a once or twice a year solution.

Tradition, I am ALWAYS barefoot, so grit unfortunately won't work for this.

So the fern thing is unwelcome? And you want to kill the fern and get the bricks clean... Do you think the ferns are shading the bricks and causing the problem to begin with? Last time I dealt with that, pulling whatever growing from the cracks also pulls all of the mortar sand. Then you need more sand, which likely had more weed seeds, and more blow in, never ending battle... I think killing the ferns and cleaning the bricks will be 2 steps, but don't know if it'll b possible within days. *IF* RU kills this fern thing, it won't be dried up and gone that fast. Don't think bleach will kill it either, but I can see where a using a paint roller would cover it and the bricks well. You'd at least get the algae off. If the ferns die, bonus - I think that's what you're saying.

Yes, exactly.
At this point, I can hand pull the weeds (ferns), and yes... It'll pull sand and mortar out.
I guess I'll do the bleach move and see where the chips fall...

Has anyone tried copper for this? I use it in a small fountain to keep the algae at bay, but not sure if it would stain the pavers.

Bayer Advanced makes an algae remover, but I think it's a chemical.

I sprinkled 20 mule team borax powder on my wet and slimy wood deck. The grit immediately made it safer and in a day or two the algae had dried up and I could hose it off.

Didn't notice any damage to the plants, but wasn't looking either. I don't like working with bleach so this is my go to solution.