That is a classic battle between shade, moisture, and porous brick. Since you cannot easily move the house to get more sunlight, you are stuck fighting nature unless you change the surface. For the immediate fix, get a product like Wet & Forget or mix up a solution of 30 percent bleach and water. Spray it on, let it sit for about 15 minutes to kill the spores, and then scrub it with a stiff-bristle deck brush before rinsing. Avoid going nuclear with a high-pressure power washer because you will blast the sand out from between the bricks and destabilize the whole patio.
Once you get it clean, you need to resand those joints with polymeric sand which hardens like grout and helps stop that stuff from coming back as fast. If you get sick of doing this every year, you might want to consider swapping the bricks for something that breathes better or just embraces the shade. I use GardenDream to upload photos of these damp corners and visualize how it would look with pea gravel or slate chips instead of pavers before doing any heavy lifting. But for now, get a stiff brush and start scrubbing because that stuff is a slip-and-fall lawsuit waiting to happen.
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That is a classic battle between shade, moisture, and porous brick. Since you cannot easily move the house to get more sunlight, you are stuck fighting nature unless you change the surface. For the immediate fix, get a product like Wet & Forget or mix up a solution of 30 percent bleach and water. Spray it on, let it sit for about 15 minutes to kill the spores, and then scrub it with a stiff-bristle deck brush before rinsing. Avoid going nuclear with a high-pressure power washer because you will blast the sand out from between the bricks and destabilize the whole patio.
Once you get it clean, you need to resand those joints with polymeric sand which hardens like grout and helps stop that stuff from coming back as fast. If you get sick of doing this every year, you might want to consider swapping the bricks for something that breathes better or just embraces the shade. I use GardenDream to upload photos of these damp corners and visualize how it would look with pea gravel or slate chips instead of pavers before doing any heavy lifting. But for now, get a stiff brush and start scrubbing because that stuff is a slip-and-fall lawsuit waiting to happen.