Trying to clean brick patio - green / black surface

[Tim K 14]

In my HOA we have a large common courtyard that is all brick, and some of the owners also have small enclosed brick patios. On my patio, and in the courtyard, we have a lot of areas where the bricks have collected algae/moss and some of the bricks even just seem to be getting a dark/black stain to them. I used my pressure washer to clean my patio and it did a good job of removing the discoloration (and covering me in muck - but I knew that was coming). However, some of the bricks still have some discoloration.

Is there a product that you would recommend for really getting the bricks clean? What about something that will help keep the problem from returning - at least slow it down? I have tried a bleach solution without much more success than pressure washing alone did.

I will probably treat my own patio as a test, but if the association needs the courtyard done I would outsource that. What should I expect / ask for from a contractor as far as what services and what cleaners should be used?

[Tmrrptr 164]

Dwell time for the proper percentage of bleach solution would most likely help.

However, bleach can be very toxic and a suitable respirator should be used.

Basically, if you have given it a try, and not gotten the best results, you get points for giving it the old college try.

Inquire with local professionals for their assessment of the job.

There are probably members here on TGS from your area.

Hopefully they will contact you!