I purchased a home about two weeks ago with an attached spa / 20,000 gallon pool.
The spa has four return jets which are just basic pool eyeball return jets, and one return jet which is actually plumbed into the pool return (I'm guessing to make sure the water doesn't get stagnate). It right now has an older 1 1/2 hp air blower on 2'' PVC pipe approximately 10 feet from the spa. During the pool inspection before buying the house, the inspection noted some issues with the blowers wiring, which was somewhat fixed by the old owners; and apparently the "bearings were going bad" and he recommended getting a new blower.
Now that i've had some time to get a better feel for the pool, and read a little more on this site, i'm considering removing the blower entirely, as the distance between the spa and the intake is literally about 10', and the when the blower is on its not only loud, but it bubbles tons of water out of the spa. I usually leave both the pool and spa suction and returns open when I run my pump and SWG so that I can turn over the water and properly chlorinate it. If I remove the blower, i understand i may have some issues with bubbles when I don't want bubbles.
What i'm wondering is can I just cap the top of the 2'' PVC, or place a jandy no lube valve at the top to stop the airflow?