Depending on what is causing your stains, it sounds like algae. I use a simple treatment that most people already have in their kitchen. I mix 7 cups vinegar, 7 cups dishwashing soap, and 1 cup baking soda. (If you need a smaller amount, mix it 3 1/2, 3 1/2 and 1/2.)
Saturate stains with mixture, let it dry completely, then hose it off.
Sounds like it's an oil based stain. Pour blue Dawn dish soap on it and allow to sit overnight, covering with plastic if necessary to keep it from drying out. Then you should be able to use a stiff bristled scrub brush to clean it away.
Every time I clean my mirrors, they end up having tons of streaks and almost look worse than before I started. What could I use to clean them that won't leave streaks...
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Depending on what is causing your stains, it sounds like algae. I use a simple treatment that most people already have in their kitchen. I mix 7 cups vinegar, 7 cups dishwashing soap, and 1 cup baking soda. (If you need a smaller amount, mix it 3 1/2, 3 1/2 and 1/2.)
Saturate stains with mixture, let it dry completely, then hose it off.
*white vinegar and liquid dish soap, I prefer Dawn.
Sounds like it's an oil based stain. Pour blue Dawn dish soap on it and allow to sit overnight, covering with plastic if necessary to keep it from drying out. Then you should be able to use a stiff bristled scrub brush to clean it away.
I would clean it well, and then seal the concrete.
bleach wash and buy clear concrete sealant