My spa has no blower, but I still have a jandy three way on the air supply line. It allows me to turn off any air to the spa jets while I'm preheating the spa. As far as the need for a blower, there are four pools on my block, all designed and built by the very same builder. All but mine have a blower. I always thought that the reason my spa didn't need a blower was that it is placed at the same water level as the pool vs all the others which are raised spas. The air intake is located 60 feet away from the spa, at my equipment pad. I probably don't get quite as much aeration on the jets as those with a blower. But it works fine.