Any precautions I should know of? got a full external clean of a house in July, which will include permanently fixed heavy duty garden furniture & sun loungers, the job will consist of pressure cleaning & soft washing using hypo. From what I understand hypo is fine on artificial grass and even a good method of cleaning it, but is anyone aware of the contrary to the above and any reasons why hypo might cause damage to the artificial grass? all other surfaces will be fine using hypo.