Outbackoz

Seems like youv'e got some good recommendations. Just a suggestion on a couple of things if your town water supply is pretty dirty, ie like in parts of Hua Hin the abrasive content in the water will shorten the life of the pressure washer so if you can use either filtered or settled tank water it will help. If your trying to remove the black algae/mould from the concrete and sand wash pre spray with liquid chlorine (sodium hypochlorite) commonly used as a sanitiser for swimming pools diluted 1/3chlorine 2/3 water. Add a small amount of liquid washing detergent to the mix. PH value is similar to cement PH 13-14 so it will not degrade the cement bond as will Hydrochloric acid. Try to spray and brush in the shade as UV in sunlight will rapidly dillute the chlorine. Leave chlorine for about 20 mins and the algae should have a slight colour change to brown Pressure wash off. Further suggest when the rsiny season comes to an end to spray the affected areas with a dilluted mix of Benzekonium Chloride (Sold here as a sanitiser from Lazada and called BKC) which is a type of cationic surfactant This will inhibit the regrowth of algae/mould but you will have to apply it on a regular basis. Be sure to use correct safety equipt procedures as liquid chlorine will strip off skin in undiluted form. Hope this helps for a loger term solution. If you can't find liquid chlorine Haiter bleach will do close to neat but a bit expensive. Hope this is f help