Consumers are free to purchase their supplies any place they chose to. Dealers try to maintain a reason, and in this case manufacturers too, to stop by once and a while for their needs. Dealers also maintain internet ordering for the customer.
For this reason, some sell Baquaspa product and have a specific territory of non-compete. Because it is incompatible with other products, it brings the customer back to a single source. Proprietary Filters from SD, HS or others also serve the purpose of maintaining customer contact. These items can also be found through different sources and on the internet at competetive prices.