You should pull up and remove weeds by hand as and when they appear. If it is a regular problem, you might need to reseal the paving. In extreme cases, the sub layer itself may need to be re-laid. You can use weed killer, however some paving can be discoloured by stronger weed killers.
Bala
Bala is a market community and community in Gwynedd, Wales. Formerly a city district, Bala lies within the historical area of Merionethshire. It lies at the north end of Llyn Tegid, 17 miles (27 km) north-east of Dolgellau, with a population taken in the United Kingdom Census 2011 of 1,974. It is bit more than one broad street, this being Stryd Fawr (High Street, literally "Great Street"). The High Street as well as its stores can be quite hectic in the summer months with lots of visitors. Bala was ranked as having the 20th highest possible portion of Welsh language speakers in Wales by selecting division, in the UK Census 2011. According to the census, 78.5% of Bala's population can talk Welsh.