deck cleaning

I built a completely pressure treated deck five years ago and stained with Sikkens. It's on the north side of the house and now is very dirty---some black spots (mold, I guess) on the rails, etc.
What's the best way to clean this without damaging the wood or stain (the stain is holding up very well). I've been told pressure washing is too tough and a no-no with pressure treated. TSP? Some of those deck cleaner/brightener products?
Thanks.
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I washed mine with a strong clorox solution to get rid of the mold (I just used a mop, and rinsed with a garden hose), and then re-stained it. The clorox takes off the black stuff (mildew) quite well. However, it's a pain to clean the railings (I imagine it's a pain with a pressure washer too).

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The household bleach (1 cup in a gallon of warm water with a little detergent or TSP added) will kill the mold. The detergent helps spread the solution and loosen the dirt. It is easier to apply it using a garden sprayer. If needed you could use a SOFT brush. Leave the solution on for 5 minutes then rinse off. If the mold has been on there for some time, a second cleaning may be needed.
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I didn't want chemicals slopping over the plants under my deck, and there was too much area to put drop cloths, (besides, it would take forever to scrub 1500sf)so I used an electric pressure washer. Okay, there were a few bits of minor damage, but overall it worked well. I think the damaged areas probably needed to be cleaned out anyhow. I first checked a number of Stain Mfg's sites; some say no pressure washers, others say none over 1300psi.
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north exposure, you probably have alot of mold, your stain may look good but you need to restain after you clean, If you dilute your bleach much you may have to redo it. I am in full shade and bleach full strength on wood and concrete. Power wash will not hurt wood, use a wider tip setting
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as someone suggested a garden sprayer is the easiest way, but be careful adding detergents to bleach anything amoniated will creat a poisonous gas
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wrote:

Jim,
I called Zinsser about Jomax. They do not recommend it for unpainted surfaces or where the finish is worn through. They recommended Wolman instead. Wolman is another Zinsser label. See www.Wolman.com. I believe the difference is oxalic acid. I have used neither product.
Joe
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In alt.home.repair

I've pressure washed PT wood decks with no trouble. Rather than buy deckwash, I mix my own combo of 2 scoops laundry detergent in a 5 gallon bucket with about 1/2 a bottle of bleach. Spray it on softly and let it soak 15 mins, then blast if off board by board. It looks brand new. And yes, let it dry thoroughly before sealing.
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CLOROX.. the best and easiest. I used a pump-up sprayer to get the railing. Rinse it and let it dry completely, then add the water seal.
Gary
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