Preventing algae growth on decks

[DaveO]

I just got done doing a repair to a deck I built several years ago. It's a ground level deck around a pool, and one of the plumbing pipes had broke, so I had to pull up quite a few deck boards to access and repair the pipe. The deck was originally stained, but hasn't been since the first application. I noticed that the deck was rather green with algae, and the homeowner asked if I knew something that would prevent the algae growth. They had recently pressure washed it, and within weeks the green came back. The deck is in a very wooded location and doesn't receive a lot of sun. Also being at ground level it doesn't get a lot of drying air flow from the underside.
Anyone know if there is a stain, sealant, or treatment that would help to prevent algae growth. It's about a 700 sq. ft. deck so it would need to be easy to apply, too :-D :-D
TIA for any advice,
Dave

 

[Travis Porter]

Dave, I would like to know the answer to this myself. I saw how to do it on a roof on TV one time. They put a piece of zinc up on the roof and the particles of zinc coming off of it prevented the stuff from going back.

 

[DaveO]

Well I did a little of my own research and found that a lot of the normal stains and oil finishes applied to decks to protect them actually provide food for algae and mildew growth. Oil based products containing linseed oil or other natural oil are great at supporting algae growth, so much that most contain ingredients to prevent algae growth, but they are water soluble formulations that quickly disperse.
It is recommended to clean the deck surface with an oxygen bleach which will kill the existing algae and mildew but not bleach the color out of the wood nor poison the landscaping around the deck (we can't have that, now can we :eusa_naug ) And then seal the deck surface with a penetrating water repellent the uses synthetic oils or resins.
I found several sources recommend a product by a company called Defy, it's an epoxy based water-born stain. I was able to find more product information here:
DEFY Epoxy Fortified Wood Stain, Defy Stain
I think that I will recommend that route to my clients as soon as the weather warms up enough to use it.
Dave

 

[jerrye]

FWIW, oxygen bleach is just hydrogen peroxide. We sell this through our commercial laundry division at work. So the next time you're tempted to buy "OxiClean" from the loudmouth on the infomercial, just go to the drugstore and buy a cheap bottle of the liquid, dilute it a little, and have at it! Or if you need A LOT (5 gallon pail or more), PM me and I'll get costs to you.