All spas have venturi jets. That's what makes the bubbles.

The reason you need a blower is because of the distance of the air pipe to the spa. If you put the air pipe within 15' of the spa, you shouldn't need a blower.

Thanks for the reply. Most pools we have seen in our area do not have venturi 'pipes' - that is, the vertical pipe from the air ring to the coping of the spa, with the 'spin value' on top. I may be using the wrong terminology. What I mean is, the spas with blowers do not have the "air valves" on the spa coping and the spas without blowers do have these. I'm thinking both would be best.

Thanks for the explanation! I had not heard of having the Venturi away from the spa, but the noise can be bothersome. I'll try to google to find out more about it.

If the plumbing is done correctly there is no need for a blower. You can even set your airline for the Venturis at the equipment set weather it is 10 feet away or 100. My average airline run is about 50 to 60 feet. Ive even done them at over 100 feet. I have all the jet power that I need without a blower. Pool plumbing is about hydraulics. Hope this helps.

The longer the air vent pipe, the larger it needs to be so I am surprised you can get 100 feet of air vent pipe and still get bubbles. How large is the pipe? Normally, this would require a blower or extremely large pipe.

While what Pools04 said is true, it will take a really long time for most jets to pull the water from the air line.

I would also add that often mas985 is correct if its flex pipe used for that line if it isn't laid straight and the elevations of the line are too low below the water line for any distance. Then the water weight overcomes the suctioning from the venturis of the jets.

Scott

Putting in a Hartford loop near the spa can help too but I have never heard/seen any air vent that long that worked without a blower.

I have two hartford loops at the spa encased in the gunite. They are done out of rigid PVC. They are one inch lines that go up to a 2" air line. Although now I've scaled it up to a 2.5" line. In the past I have done the 2" line and it took no time for the jets to get going. That was even at 100'. If your flow going back to the venturi's is done correctly they will pull air.

Pools94 - Man, would I love to see a photo of THAT! It never occurred to me I could put a hartford loop in the spa wall! It'd have to be close tolerances to be sure to be above the water and below the coping, but I can see how it could be done now that you put me onto the idea.
I'm just now puzzling out whether or not I can even HAVE air. For one thing, my pump Must be set up below the water line, and about 35 feet away. I know the advice is to have the air blower above the waterline, but it's just not possible here. I'm putting the electric heater in a gazebo basement to avoid freezing and (if I have a blower) it'd have to be in there too. Now you've got me thinking I could have venturi air without topside air valves? I considered not having air at all because I don't like the looks of those valves. How do you turn the air on and off while using the spa? Can you?
Please go into more detail of how you did this; I'm doing a DYI cinder block spa using Gene Trumbal's book and video.
In the attached photo you can see my spa project outlined in the dirt. I've spent the past 12 years building this house and brick oven gazebo. The spa is the final big challenge.

wrong pic before. that is the gazebo last year. I'm farther along now. Here's the model (I hope)!

THIS is the gazebo today. You can see the tile mural I'm doing on the arch of the oven inside. I'm making a landscape and the oven opening is the rising sun. Anyway, to the point: This structure has a basement and that's where the electric heater will be and if I use a blower it'll have to be down there too- but the whole distance and hartford loop thing has me baffled at the moment. I'd like any advice I can get! PLEEEEEEEZ ;-o
The filter, chlorine generator and HE are to be piped from the back room in the house where my boiler room and solar storage will hook it all up. That will take care of maintenance temps and the elec heater in the gazebo basement will be for time of use heat-ups