How do I remove algae from a deck?

A

AlastairSC

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It's about 2 years old. Pressure-treated softwood, smooth side up. Never treated or stained. Perfectly sound, if a little weathered. Lots of green algae stuff.

We tried Ronseal Deck Cleaner but we were surprised when it had almost no effect. Instructions said pour onto deck, scrub in, and wash off after 15-20 mins. It certainly didn't do exactly what it said on the tin!! The pressure washer cleaned the dirt off but the boards that were the worst (under trees) are still as green as ever. It's not the original preservative either- it's the algae.

Are we missing something? What can we use now?
 
You really need a "hot" pressure pressure either deisel or electric the very hot water put out by these cleaners will remove anything
 
I've done it with a cold pressure washer with great success. messy messy job though...you need wellies/water proof trousers and jacket.

I had borrowed the pressure washer.
I borrowed the same one 2 years later for the same job and found it MUCH less effective.
So I guess I'm saying you might be better renting a good one, rather than buying one as they seem to loose power.
 
I agree a bit of chlorine/bleach in the water will kill off the algae
 
Thanks for those, folks. I'm puzzled now. Our pressure washer is of the cold variety - connects to garden tap. Where do I put the bleach? The internal reservoir is small and I thought this was just for use with the little rotary brush? Hugely powerful with the lance attachment (can damage the surface of the timber if held too close) but just piddles water with the rotary brush. I've been pouring the stuff directly onto the deck like it says and then using the lance....
 
Could try a bit of homemade weedkiller maybe (vinegar/salt/soap) and let it soak for a day or so and then powerhose off? At least the wood won't get bleached if that concerns you.
 
AlastairSC said:
Thanks for those, folks. I'm puzzled now. Our pressure washer is of the cold variety - connects to garden tap. Where do I put the bleach? The internal reservoir is small and I thought this was just for use with the little rotary brush? Hugely powerful with the lance attachment (can damage the surface of the timber if held too close) but just piddles water with the rotary brush. I've been pouring the stuff directly onto the deck like it says and then using the lance....
Click to expand...

The pressure washer alone is enough without the need for any detergents or bleach. It takes a while depending on the decking, but with a steady hand and patience it'll come off and the decking will look like new.
 
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