I am in the process of painting my porch flooring. In the past, oil based paints have been applied. I have had to replace some rotten boards which are pressure treated. I would like to know the proper way to treat new wood for paint. I have been told that pressure treated wood can been treated for 45 minutes with a soap - water mixture and rinsed. After one week I can paint it without out worry of peeling, etc. Please advise if this is appropriate.

Also, should I lightly sand and wipe the existing painted wood in order to have better contact to the wood by the new paint?

Thanks much for your help.