Need advice on our concrete patio: Mold/mildew off and then paint or stain or ?

Our 18 y.o. concrete pool patio (and walkway to front door) are not looking good. We got here 6 years ago and I don't know if it was ever resealed.

Some concrete in the shade and under trees has green to black mold/mildew. Is this Strachybotrys alta? Read some posts here about detergents, bleach, TSP, etc. Nothing about power washing, which we have done in the past and seems to work OK until the rains come. Another remedy I came across is using a pH neutral or alkaline cleaner such as Oxyclean (sodium percarbonate) and detergent, rinse and dry throughly. Anyone tried this?

If we clean the concrete and promptly use a concrete sealer.....will that prevent mold/mildew from coming back?

There are paints and stains we might use. Some advertise they are mildew resistant. Is this true? I know you can add a few drops of mildewcide to a gallon of house paint. Hold true for outdoor concrete paint/stain?

We have about 335 sq. ft. of concrete. Should I find a licensed contractor to do the job?

 

I had about 400 sf poured, stamped stained and sealed this past week for a client. I leave it to the pros. It turned out spectacular. I don't know how the staining goes, but the sealing must be done after it is completely dry. They put on an initial coat, then rolled on a second thicker layer the next day. If it is done after it is dry, I would think it would help to keep any mildew on the surface of the sealer, which would make it easier to rid with soap and water rinse. This was a dirt area, 6" down from the threshold.

 

So I'm back about a year later....and nothing done. I did see a Danny Lipford segment on HGTV where he used a spray bottle of "Mold Control" by Concrobium. He said it works but did not show much more in the way of results.

I emailed the company to find that it will NOT remove the mildew or mold, but it will destroy and encapsulate the critters to prevent further growth.

It seems that power washing to get a clean surface, followed by a layer of "Mold Control", could be the way to go.....and eliminate power washing next year and future years.

Anyone used Concrobium "Mold Control" ??

Thanks in advance

 

I usually use a pump up garden sprayer to apply a bleach/water mixture and the a PWer to rinse. It's cheap and effective. A water hose can be used instead of the PWer. Sealing the concrete should slow done the mildew growth and make cleaning easier. The longer the patio stays wet, the more apt mold/mildew is to grow.