After a deep wash, it's important to restore and secure the sand, as this is what keeps the pavers from moving and weeds from growing in. The approach that worked best for me was essentially sealing sand between pavers to prevent the seams from being washed out by rain. Pressure-controlled equipment helps with pre-cleaning, and I've noticed that effective cleaning products are usually labeled as pressure washer paver cleaner, which reduces the risk of efflorescence and stains. Have you noticed that ants stop stirring up sand after sealing the joints?