Posted: 16/11/2013 at 14:14
I have a firend with the same problem and who isplanning to replace her decking with stone paving slabs. Not sure how that will work as on my shady terrace made from recycled granite pavers it always gets slippery in wet weather and all through winter.
Pressure washing is not ideal for wood as it destroys the surface and lets more water penetrate which can lead to premature rotting. You can use a special spray to prevent algae forming but be careful not to get it on precious plants either side.
You can also stretch chicken wire very tautly across the decking and bridge and staple it down. Try it on the bridge first to see how it looks and works. It will soon weather and blend in and will give you grip.