How to clean a grubby black dirty old cement porch

Get a good stiff brush on a pole, and scrub it with hot water and lemon ammonia. Let sit a few minutes, and hose off. This should also remove any black mold thats on the surface too. You could also use Wet n Forget.

Pressure washer

I rented a power washer and my patio and drive way looks so much nice.

Definitely rent or purchase a power washer. A friend came over to do ours and I couldn't believe the difference!

I agree with the folks above, a pressure washer works wonders. And you can purchase cleaner (Krud Kutter, I believe) to get an even better clean. Good luck!

Use a power washer and krud kutter.

Nothing a bit of elbow grease can't fix. I would start with Dawn dishsoap and vinegar and a stiff bristle long handled broom. If that is not successful, I would try a driveway degreaser.

use swimming pool acid.just wear protective clohin

power washer?