I have a 20*40 liner pool with a small round Spillover SPA. (I think its a Triac) My set-up has one pump and one heater all controlled with a Jandy Aqua Link system. My SPA also has a manual valve at it that is used to adjust the amount of air it introduces to the tub. Can I install a booster pump or blower to boost the spa's action ?

Currently, my overflow spa has two small manual valves next to the spa that you can unscrew to allow air to mix. I had the option of adding a blower, but friends never use theirs as it is too powerful and cools the water quickly. However, when the system was plumbed, the air line was capped and burried outside the spa and my PB said it could be used if I ever decided to hook up a blower to add air, instead of the current venturi ones.

I'm not sure, but I think a booster pump would restrict flow when not on. Normally, a spa will have a separate high flow pump that is on a completely separate inlet and outlet line as the filter ciculation lines.

Thanks for the great information but it looks like it's a no go for my situation because my tub is surrounded by concrete that I don't want to break up. Was hoping I could put something in the lines by the pool equipment but I don't think that's a option. I have had my pool for 5 years and it seemed powerfull enough until my neighbor put one in with a booster pump and blower that really seems nice. Maybe it's just because it's new and they wont end up using it much either.

Any spa that has venturi jets should have a vent pipe where the air is drawn in. You could put a blower on this air pipe to increase the air unless that is what you are describing as being in the concrete. However, adding a blower just increases the amont of air but not necessarily the strength of the jet. Given that water is much heavier than air, the strength of a jet is determined by the pump's flow rate rather than the amount of air. However, if the venturis are not drawing in enough air due to a small vent pipe, then a blower can help some.